I have not tried to contact them yet, but I have heard that these guys are pretty much the best source of parts (and knowledge) for these old Belleview/Warn winches:
The 4 Wheel Drive Center of Minnesota, Inc
5711 West 36th St.
St. Louis Park, MN 55416
952-927-8811 or 800-328-4445
I have one of these winches that needs rebuilding one of these days. Just too many other projects right now.