pentax lens mount screws stripped...

I was just trying to figure out why the auto focus and auto flash pop-up
on the MZ7 I picked up (not so recently) on ebay was getting finicky,
and saw that the some contacts were almost flush due to the screw's
being loose on the lens mount ring. I managed to get them tight enough
that everything contacts ok now and it works, but I think I'm going to
have to replace the piece that the lens mount screws in to.

Is this terribly difficult to do?, or should I take it to a camera
repair depot (3 hours away). It looks to me like it is screwed in to the
camera body itself and *may* not be to difficult to replace.

Should I attempt this or just drop it off next time I'm in the city?

Does anyone have idea how expen$ive this piece might be?


thanks in advance...