I think it's also A LOT about shoulder balance.
I think I also had a problem with a ligament moving cause it feels like something is jumping around in my shoulder.
Remember to train all three heads and bring up the lagging ones.
I know I talk a lot about gear, but my shoulder never felt better than when I first did injectable steroids. My shoulders equalled out and became a lot more stabilised, and I even think steroids should be legal for this purpose.
Do lighter weights and higher reps to get more of a pump and more stability in there. Don't forget to train smart.
This is what works for me, I just came back from a shoulder workout:
Smith machine presses to the front
Smith machine behind the neck presses (nothing too heavy)
Seated bent over rear lateral raises
Upright cable rows
Standing side lateral raises
10 mins of my fat ass on the treadmill at a quick walking pace