Join Date: Mar 2006
Location: New England
Thanked 15 Times in 12 Posts
Rep Power: 14
Ahh, the joys of galvanic corrosion. You will need to drill out the screws holding the winch in place. The screws have galvanically corroded, and are now bonded to the mast via the corrosion.
Ideally, you could just drill out the screw heads and then lift off the winch, and then deal with the remaining parts of the screws once the winch had been removed, but I don't know how likely this is to work. It depends on the number, location and alignment of the existing screws.