i guess you mean the 6 sided allen hole is stripped.. rounded.
if you can get in there, cut a straight slot in it's head with a Dremel and one of the little 1" diameter cut-off wheels. Then use a flat screwdriver bit to get it out. You may have to cut into the case a little to get the slot deep enough..
another thing that might work.. do you own an Impact Driver The kind you hit with a hammer?
..mm.. never mind.. i find this too complicated to explain .. (basically find a 3 or 6 sided bit, shape it to fit tight in the stripped allen head and use the impact driver)
The cut-off wheel thing has worked for me many times in many situations.
i save worn cut-off wheels .. when they get down to about 1/2 inch diameter they fit in places a new wheel won't.
get an impact driver if you dont have one.. and get a set of bits for it (rig something up with a socket or whatever) that fit your case screws, whether they be allen or phillips or whatever... Case screws tend to tighten up with engine vibration and become a real bitch to remove. An impact driver never fails to get them started out.