I tackled that job once and it was not too bad, but I didn't have any damage. It's worth it I think for a look see. You can always put it back in and hold it in with several screws and take it too a pro. Use a drill and proper bit and undo all the screws. The window won't fall out. You have to pull the frame away from the old caulking. Gently go at it from one corner and pull it away from the body and the caulk will yield. Once it's out you'll know your situation. For me it was as simple as running some new caulk around the outside, then fit it back in and screw it down.
