Hayabusa --I tore my supraspinatus(rotator cuff)--full thickness tear, had surgery in 2004, rehabbed myself (I have 5 years physical therapy experience) 6 months afterwards started to lift again was 100% better...well last Saturday, while doing heavy dumbbells shoulder presses, it felt kinda funny. I iced it 3x a day for 20 minutes, and took Advil. Stopped all upper body exercises!!! Just got my MRI report, partial tear. I am training through it. Doing internal/external rotations, rev pec-dec, seated row with a pinch (squeeze shoulder blades together at end of movement) and light bicep and tricep work. Do this as your PT exercises 4x a week! My shoulder is feeling much better in 1 week. The bicep and tricep attach to the shoulder. You are going to have to train them light with a pain free movement. Maybe try seated dumbbell curls and work through a "pain free" range of motion. Try 12-15 reps, get fresh blood and oxygen to the muscle to repair it..And ice it as much as possible to avoid any inflammation. Take 10-15 days off all chest/shoulder work..DON'T WORRY YOU WILL NOT GET SMALL!!! Resume shoulder/chest work with machine exercise, week 1 20reps, week 2 15 reps, week 3 12 reps and week 4 10 reps. If pain free at week 4 with 10 - reps on machine work, progress to light dumbbell work. It is up to you and your orthopod. IF you choose surgery. Most partial tears can be healed with PT work, and I had some experience with full-thickness tears also healing with just PT. Hit me up with an e-mail if you need more help!
Good luck!