15 yr old gelding wont take the bit

i have had him almost a year, at first everything was fine he started to lift his head out of my reach , side step,.rear up the whole nine, i fiqure Pain , vet came checked his teeth ,floated them , still a fight , once or twice will stand and then well he dont want to work, he basically is a very good horse has some quirks that had to be addressed, bad feet ,split hoofs ,not fed properly, i have been the only one to bridle him so I know he was not handled roughly here any suggestion how to reintroduce the bridle gently and to build more of his trust? oh i bought him from an auction I have had to bring him around once or twice to trust me its like he forgets Im a good guy

No one has said this yet, so I'm gonna suggest... check his ears. One of my favorite school horses absolutely hates to be bridled and it's not because of the bit... she's absolutely wonderful for everything, but she acts up when you bridle her and it's because she has a fungus in her ears and she knows that if she takes the bit, you're gonna lift the bridle over her ears and it's gonna hurt. I tried taking the bridle apart and setting it over her head first, but she still has that idea that taking the bit makes her ears hurt... I think if everyone took the bridle apart like I do, she'd eventually learn that it doesn't hurt anymore.

So my advice is to check your horse over again... it might be something really random that's hurting him and it might have absolutely nothing to do with the bit. Try touching his ears when he's just standing with you and see how he reacts. Try taking the bridle apart and setting it on him before putting the bit in his mouth. If you decide that it is the bit that bothers him, the hackamore is a pretty good idea.