Cant get the left lead

Question
I am retrainning my 5 yr OTTB who came off the track in september. We have no problem getting the right lead, just the left. I have tried to bend him slightly to the outside, and bend him to the inside and nothing has worked. I have tried to pick it up in the corner or on a straight line. Ocassionally he will pick it up on the straight line. I have tried to carry a crop (not use but just carry it) and when I do he just throws his head up in the air and gets all fast. Or the only way he will may be get it is by droping his should horribly ( I mean he almost falls over) but at the walk and trot he is balanced and able to frame 90% of the time.  HOw do I stop the shoulder dropping to? WHat do you suggest to do to get the left lead canter?
He is riden in a mullen mouth eggbut snaffle should I switch to a loose ring? If I remember I think I rode him in a dee ring when I first got him. He was fine to canter both ways when I got him so could it be the bit? He seems to be confused, and I have tried to find his"button" but obviously am failing. I do nothing different from how I ask for the right lead.
Heather

Answer
Hi Heather,
Seems as if overall you are making good progress with your relatively new horse.  That's good. Don't worry, you'll eventually get where you want -- re: pickin up leads.  It is normal to "regress" a bit if you will -- you say he used to pick up both leads, now he doesn't.  Don't let it bother you too much -- you will get it back! Here are some tips.

>>He seems to be confused, and I have tried to find his"button"
He probably is confused!  Moreover, he might not have a button!! You will need to educate him, create a button.  His former training may have holes in it, and communication to his riders was very likely more sloppy than the type of communication you strive for in either dressage or hunter-jumper.

>> He is riden in a mullen mouth eggbut snaffle should I switch to a loose ring?
It doesn't matter.  I prefer eggbut because they do not pinch the corners of the mouth.  Loose ring can pinch.  Good hands matter.  Also, I hope the bit is not too thin, nor too thick. But mainly, I'll remind you that the *key* to canter starts and choosing leads is in how your seat / legs cue the horses HIND legs.   I can start my mare in a canter lead of my choice bridleless, from a standstill, or from a walk, or from trotting.  

>>I have tried to carry a crop (not use but just carry it) and when I do he just throws his head up in the air and gets all fast.
They use crops on the track.  No wonder he expects no good when he sees a crop.  Also, remember that in a race they *pull* on the bit. Hands are not necessarily soft and giving, nor gently supportive. (not by my definition!)  So horse sees crop, expects to be urged on and hurt in the mouth at the same time!!!  I would get crancky also if someone did that to me. I'll tell you how you may use a crop to your advantage below.

>>I have tried to bend him slightly to the outside, and bend him to the inside and nothing has worked.
Heather, congratulate yourself on trying different approaches :) don't give up on trying new (gentle) ways.  Sometimes, very little adjustmenst in your own seat, hands, legs, etc, allow the horse to adjust his back, and get better.  Compare it to how small adjustments in a heavy backpack make a big difference to you, if you have to hike all the way up some mountain with that backpack.
That said, I can tell that you know that bending to the outside is incorrect.  Yes, it works for some "dudes" or for green horses-- sometimes -- but it is not correct for many reasons having to do with balance and self-carriage.

>>HOw do I stop the shoulder dropping to? WHat do you suggest to do to get the left lead canter?
I'll give you some tips here.  Keep in mind I could write a treatise -- as many elements come together in a harmonious ride.  
-- about the shoulder:
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   I teach the "bend" at the shoulder from the ground.  Keywords:  move away from pressure, yielding.  As soon as the horse yields, release and praise.
   At a standstill, in the saddle:  (I'll use "left" but should work on both sides)
--pick up left rein, bring horses nose around. (hand should be a foot from withers, right hand at withers) Hold.  When horse looks at you, release.  
-- if horses' head is not vertical, ask him to move his hindquarters one step over.  Wait for horse to look at you ("give") and release ASAP.  Release does not mean let him pull the rein thru your fingers. Release means you open your hand ASAP completely -- we do not want to teach him that he can slide the reind thru your hand.
As you ask for the head to bend, watch the jawline. Where does it turn?
Ask for bending of the head a lot -- John Lyons sais 500 times!!!
--- also at a standtstill, long reins:  can you turn your body left, move your left leg behind the girth, and very lightly tapp behind the girth? will your horse step the hindquarter over to the right (away from your left leg) *without* stepping forwards?   Stop tapping as a reward for moving, regardless, but if he steps forwards, pick up on the left rein and bend the head as above. Praise when he stops, softly.
-- do it to the right:  can you, with your right leg behind the girth, lightly tap-tap signal your horse to move the right hind leg under neath?  One step only?  Again, with your right leg behind the girth, ask your horse to step his hindquarters, from a standstill, over to the left (away from your right leg behind girth.)  Tap as lightly as you possibly can!!!  Even simply shifting my leg position can be a cue on a finished horse.  When the horse steps over behind -- one step -- stop, praise.  If he goes forwards, pick up the right rein and bend his head to the right, release leg, wait with hand, release the rein when the horse looks at you.  
Do this a lot -- your goal:  be able to ask the horse to turn his head without him moving his feet.  Be able to ask your horse to step over with his hindquarters left of right, without him moving on, even on long reins
Tip:  try these exercises after your regular warm up.  Don't attempt on a totally fidgety horse at this stage.

What you did if you practice the above is teach your horse to step over behind.  IF your horse moves his right leg and steps under himself WHEN you ask with your right leg slightly behind the girth -- THAT is your signal to canter, left lead!!!!
(a horse picks up a left lead starting by using his right hind deep under himself)  All you need is turn up the speed.

1. exercise tip for canter left:
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practice lots of circles to the RIGHT!!!! yes, because you want the right hind flexed.
practice shoulder ins, while circling left:  because you want to not drop the left shoulder.  

Start canter from circling left.  As long as you are on a general "circle left" position, don't worry too much about corners or straightness (untill you get the left lead going better.)  It's hard enought to concentrate on one thing (the left lead), so don't worry too much about arena patterns.
But do use your reins to support the horse.  Use your left rein to bend the horse's head, and if you think he'll drop his shoulder, keep the left hand a bit away from withers, and a bit higher than you would in competition.  You are schooling now.
Mainly, if for one or two strides, he goes well, REWARD by slowing him down and praising!!!!  Don't try to keep it, untill it falls apart on you.
Check your own body balance.  Are your shoulders, back and seat balanced?  Most of us are not exactly symmetrical in our riding, and it carries to our horses.
Check saddle.  Check horses' back manually, look for possible sore spots, saddle fitting , etc.
Lastly:  are you the only rider ? If the horse is ridden by other people.... it's not helping.
As you know:  spend most of your time at walk, trot.  Lots of circles, snakelines, shoulder ins,
Cavaletti and trailriding build muscle and flexions.
and....
one more thing: I repeat, because it's important.
when you get the left lead, praise, and gently (but soon) bring him down to trot or lively walk!!!  Reward him for taking the left lead, ASAP :) and do not try to maintain it.  I want you to stop  him, before the quality of your left canter falls apart.

2nd exercise to pick up a lead:
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set up a cross rail low cavaletti - jump on a diagonal.  No poles before.   Pick up a right lead canter, go to the right, then after the corner, canter along the diagonal.  Prepare your body to change to left as he jumps the crossrail and take his nose left as he jumps.  He'll likely take the left lead at landing.  If not, repeat.  Be sure that you change your body.  
Technically, I'd say ok, your body is set on "right canter.".  One stride before the jump, straighten your body.  CHange to left over the jump.   You're allowing your horse to change leads -- most of them will do it naturally.  Then rub and praise him as he canters off to the left....

For this exercise: do not attempt perfect collection.  At this stage in training, allow your horse a bit of speed. (should he be natuarally "lazy" encourage some more life!)  Not dangerous, just don't expect perfection. He may not have the conditioning for collection, nor the mental readiness.

Hope this helps, Rena