I have been inspecting the masts further. I started to remove some of the masthead hardware. It required tools including a can of WD-40 and a 5 lb sledge. Basically, things were pretty scary. For example, the tangs for anchoring the top of the shrouds was secured with one big 3/4 in stainless steel bolt, through the aluminum mast, secured with a big FERROUS steel nut (read: it was a big piece of orange rust). I got the nut off with some work, but the SS bolt is still seized in the mast.
30 Year Old Technology
The masthead sheaves were all seized up. The SS clevis pins holding them in came out ok. But I had to whack the sheaves with a hammer to loosen them and slide them though the top. It looks like all the masthead sheaves are is these big aluminum sheaves spinning on stainless steel clevis pins. Metal on metal. Something you never see these days. Inspecting the sheaves reveals quite a bit of corrosion. I guess something to be expected after 30 years. But, heck, even our 25 year old sloop has a better masthead setup than this!
But, this can be easily remedied. Replacement composite sheaves can easily be had. Including ball-bearing sheaves.