If memory serves, theyíre either T10 or T15 Torx heads. If you have to ask that question, Iíd ask if you have the expertise to go inside of that thing with out doing further damage. Thereís quite a bit of sensitive parts and circuitry involved as specially around the compass head and that red trim around itís midships is actually a seal which can be a bit of a bother to properly put back in place. The plastic in those older ones can get quite brittle and they donít take too kindly to flexing or being forced. Iíd recommend taking it to someone with a background in repairing electrical and mechanical items. It may not be rocket science but itís $400 in the trashcan if you screw it up!