Wildtoy,

I've had this problem before and ended up rivetting stainless steel 50 mm long chainplates; Ronstan RF27 I think over the mast rotator on each side of the mast and drilling the centre hole out to take the rotator arm bolt (1/4" dia.) that goes all the way through the mast.

Use plenty of Duralac on both mast and the chainplates to prevent further corrosion and help seal the corroded area and don't forget to completely Duralac the rivets as well.

You'll probably still need to invest in a new mast but this will probably give you a bit more life out of the old stick. <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />

Regards,

Peter

p.s. dig out as much of the corrosion as you can with a knife or old screwdriver to prevent further oxidization but don't go overboard otherwise you may end up with too many holes and nothing left of the mast. <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" />