bucking while jumping - HELP

So , I have a 16.2hh hanoverian gelding called felix , in canter he can buck sometimes and sometimes her doesnt , but when I jump , he bucks constantly up to it if it is more than say 3ft high. When I do grids he is fine but when it is a single jump he bucks and is very strong too and he can sometimes knock it as he is going so fast. Any ideas that could help with his bucking and tanking off problem , any ideas will be much apreaciated :)

After the jump I assume? How's your bit pressure after the jump?

Actually mostly before, its quite odd ! , I try not to pull back as I know it will make it worse so he doesnt have a lot of pressure in his mouth.

First things first....have ALL pain issues been rulled out?

Does your saddle fit ?

Do you have any videos ?

To me , this would seem to indicate that he is anticipating pain with the jump. IN the grid, he may be too busy just naviagting the jumps to anticiapate the pain or buck.

Videos?

I'd love to hear more to be able to help. Everyone here has asked wonderful questions, and before proceeding, most important is to rule out pain issues. If a horse is bucking on the approach, that tells me there is some sort of concern or anticipation of something unpleasant. Check for pain, and then go from there.

Pain is the most common cause of bucking. Usually saddle pain or rider caused (snatching his mouth, sitting down to early, bumping with spurs), but with jumping you need to also consider leg pain. Have him gone over by a vet and farrier.

Does he only buck when you ride or does he also buck for others? If you lunge him or free jump him does he buck? How do you ride differently to and through a grid?