Had my compass rebuilt in Annapolis 2 winters ago. As others have said , mine also lifted twisted off.this revealed a bracket mounted with 4 long bolts seized quite heavily. Bought a large slotted screwdriver with a square shaft. The fit was snug. Used full body weight on screwdriver and a friend turned shaft with a wrench. Carefully and with heavy pressure got them out. Replaced with new ss Philips with anti seize. Also replaced steering cables while I was at it. Good luck! BTW They didn't break free, just moved incrementally an eighth of a turn at a time, Major PIA