Doesn't Like The Saddle Going On
If the saddle is uncomfortable, your horse will not want you to put it on its back. To stop you from doing this he may exhibit some or all of various different behaviours. He may walk round the stable while you are trying to put it on, or manoeuvre himself to try to escape you. He may kick out while you are putting it on or he may try and bite you while you are putting it on
Use The Perfect Fit Saddle Fitting Kit to check if the saddle fits. If it doesn't, be sure you get one that does and don't ride him in the old saddle until you have. Using the kit, check the saddle's fit at least every month, or more often if there are changes to your horse's diet or exercise.
When you are certain that the saddle fits well, it could be that your horse remembers the pain that he was in previously, or, he is still in pain from the damage done by that saddle. If this is the case, you must have his back checked by an equine physiotherapist, chiropractor or osteopath. In fact, if a horse exhibits any unpleasant behaviour, the first thing to do is have him checked out by one of these professionals.
Sometimes it can take a while for a horse to trust that the saddle isn't hurting him, so be patient with him if he takes a while to become relaxed in the process.