So, the empty can test hurts, but you're able to hold your arm up against the resistance? If so, then you probably don't have a tear in your supraspinatus; or at least not a very big one. The clunk makes it sound like the entire shoulder is subluxing (partially dislocating) when you move it. If that's the case you might be looking at a shoulder arthroplasty/hemiarthroplasty rather than a rotator cuff repair. Or you might get lucky and it be a labral tear rather than subluxing. If you do end up having to have surgery, I agree with BR on not having it at the VA. The post-op patients I've had from the VA have had very mixed results.