Thanks for the help. I also have trouble getting my horse to 'soften' so these tips will come in handy.
Another method is doing neck bending exsurcises on the ground in a halter.Then do the same in the saddle with a halter.Once she becomes soft and supple move up to a snaffle bit.
Yes, you must teach your horse to "give" to the snaffle bit again. Using harsher bits won't solve the problem.
I agree with Elaine about teaching the horse to yield to pressure with a halter. Please don't use strong bits and all that aversive tack. I have a Fjord and a draught cross mare myself and I got the best results teaching them to yield to pressure by using a rope halter + clicker-training (reward EACH AND EVERY TRY and don't use a clicker if you don't feel like it but REWARD!!!). Why should horses be punished for being what they have been bred for???
Definitely good advice. My horse can be a big, lazy baby, and doesn't always listen to my cues. As a result, there was a lot of pulling, which, of course, resulted in a hard mouth. Then I tried retraining. I had to retrain my mare to listen to a snaffle, and believe me, she now has a very soft mouth and is very responsive! Also, in regards to snaffles, if your horse doesn't usually do well in a snaffle, it might be because they don't like jointed bits. My girl hates a jointed bit, but she is very, very compliant to the slightest squeeze of her mullen mouth snaffle!