Fixing Shoulder Without Surgery?

I’m working on Bench, I’m way behind on power/weight but i’ll get there. My issue is a shoulder injury.
2 deg AC separation (RT), this is chronic, ie cant be fixed, im stuck with it, happened back in 84, during military training.

issue is when i get to heavier weight on the Bench my right shoulder starts to give, ie right side shifts with weight, only reason i realized this was when i went to rack the RT side was below the rack hook, a lil extra exertion and it racked, I’ve watched it closely ever since, from about 215lbs and up it starts to shift.

How do i correct/compensate it other than surgery. Uncle Sam fixed it once and i’m not going to the butcher shop again. Ideas, Exercise’s, any help would be greatly appreciated.