The swivel on my 1986 Mango with power furling is similar, thought not exactly the same. There are several seals and bearings in the assembly. I was able to replace all of the parts with the numbers that were still visible. The bearings were pretty much dust. After removing the seals, I had to take the unit to a machine shop to press it apart. When I reassembled with new parts, it was too stiff. I still haven't sorted this out, but I think lots of silicone grease is needed.
I would love to hear more experiences with these older swivels. They are not the same as the SM swivels.
