Old Profurl, strange new noise... advice?

[CO32_Tazling]

My good old Contessa 32 came with a Profurl unit, probably made in the mid-80's, probably (going by online photos) an N42. It has served me well for 5 seasons, some of it fairly heavy sailing. Never had an issue with it.

So it is Spring and time to bend the new sails on, which I did today. The genoa is a difficult hoist (I think the Profurl extrusion is just a tick small for my luff tape), but it went up OK. When it was time to roll it up, I got a nasty surprise.

During the roll-up, the Profurl unit made a very strange "tick" or "clunk" sound at a consistent rotation, i.e. one clunk per rotation, always in the same position. Also, it juddered or jumped a little with each clunk (as if something inside was riding up over something else, then falling back down into a normal position). I was gobsmacked: it's never done that before. Since taking the sails off last winter, the boat has sat quietly at a somewhat protected dock. There have been windy and rainy days of course, and some snow, but that furler hasn't been rotated for months. How, I ask myself, can it have broken while doing nothing?

While grasping for explanations, I recall that in January I replaced the ancient bimini with a hard-topped version. This involved temporarily removing the backstay, which of course would have slackened the forestay. So I wonder whether there is something (??) inside the Profurl that, under inadequate tension, might have slipped or slid into a location that would rub on the mechanism as it turns. I restored the backstay carefully to its original tension when the bimini was complete, so again I'm surprised that there would be such a noticeable change.

I don't think the bearing races are going, because I would expect that to produce more of a continuous grinding or growling effect, and also difficulty of furling/unfurling. The rotation is just as smooth as it ever was, and no more difficult, except in that one location where there is a hiccup.

I know that sound transmits well over wires under tension, so it's just possible that the interference is at the masthead and I'm hearing the noise down at deck level; but using binocs I was unable to see anything peculiar happening up there, and I would swear the noise is coming from inside the drum assembly.

I took a quick look at Profurl's minimalist documentation, and didn't get much out of it.

Anyway, the season is just beginning and I have enough projects to do -- so this mysterious new noise and weird behaviour are very unwelcome. My Profurl must be over 30 years old by now, so it's gonna be impossible to get replacement parts. My online reading suggests that taking apart a unit this old is a high-risk venture (it may not come apart, or it may be damaged by extreme measures needed to disassemble).

So if this leads to complete failure then I'll be shopping for a whole new roller furling setup (ouch) and a rigger to install it (double ouch). And just at the worst time of year. So I am rather anxious about it and would love to hear from anyone who has ever seen/heard anything similar.