Do v poles, put one end of the poles on the jump and one on the floor so it's more inviting. Also do lots of cross poles as it draws them to the centre of the jump more
Look up holly Lenahen on yt and watch her jumping exercises vid it's helpful
Also running out can from lack of steering, maybe try shorter reins and and a straight approach to the jump. Maybe also try walking over poles on the ground with good entry and exit, then try with X Rails and this will direct him to the centre and later try vertices. Maybe use jumps with coloured centre and look at the middle of this centre to encourage you to jump it in the right position. Also make sure you have a secure position on approach to the jump, heels down and shoulders back and leg on.
Ya! So when u are jumping and then have poles coming off of the jump if that makes sense