You can get a rebuild kit from Midwest Gunworks for $125 (they list on gunbroker.com). It includes firing pins, two sets of beads (pigeon and field), a locking plate and some other parts I don't remember. Midwest will also rebuild the action for you.
From your description it is most likely wear on the locking plate.
If it holds a dollar bill when closed, I would not be afraid to shoot it. I don't think that you would cause any additional damage at this point.
I would purchase the rebuild kit, use it for the rest of the season and have it rebuilt during the off season.
