I had the same problem with the Lofrans anchor winch... serious corrosion in the base so much so the mounting studs came out., thankfully not in a perilous situation!
The cost of a new outer case was prohibitive so I got an engineering company to basically slice off the corroded bottom of the winch whereupon a new flat plate of aluminium, about 17mm thick was keyed and bolted to the unit. This new base plate was tapped for 4 mounting bolts in the same positions as originally.Then I made up a 12mm base plate of polypropylene ( a plastic cutting board from Kmart!), drilled to allow the mounting bolts to pass thru, and used a similar piece of board to make a backing plate under the plywood platform of the anchor chain locker. It now works like new and the aluminium base is high and dry on the rubber gasket. And it's worth doing an oil change on the winch while its out!