It's a Crescent "Bridge Gun Co" 12 ga. that I'm rehabbing into a"functioning" wall hanger. No matter what I try the top lever screw won't budge.The screw has been severely buggered (partly guilty) Tried to soak in Kroil for past 2 wks, gently tapping area w/pean hammer-no go, also tried heat but so far zip. I'm reluctant to drill/tap for Allen screw, as I don't know if I can replace the original. Any advise deeply appreciate.