[squirrel_hunter]

So my approach would be to confirm the threads a stripped. Take the cover off and check the thread out. You may be in luck and there may be more thread in there to enable you to use a longer bolt. Which makes me think, are you sure you are using the correct bolt? After that its really just a case of tapping a new thread either by cleaning up the original or going oversize if there is enough meat in the case to enable that. Alternatively a helicoil insert might help.

Have you got a picture of the offending bolt hole?