Today I investigated the problem, because tomorrow I have to drop one of our cars off at the mechanic's place in Gilford before riding 25 miles back to Wolfe City to work. At the end of the day I'll ride the remaining 15 miles back home. I want the bike in good form, even though I feel old and tired.
The noise could have been a loose cassette. The cause of that could be as simple as a loose lock ring or as dire as a cracked freehub body. The old Sachs Quartz hub in that wheel was a warranty replacement after the freehub body cracked on the first Sachs Quartz hub I'd bought for a mountain bike wheel set I was building.
The freehub body was fine. The lock ring had not been particularly loose. The cogs aren't badly worn, even though they're seen the coming and going of more chains than I can remember. I try to change the chain soon enough to avoid bad cog wear. I did add a washer under the axle spacer on the right side to try to keep a seal from binding on the freehub body. To fit the space I used one of those annoying chainring spacers that came on badly designed Shimano cranks in the late 1980s and early 1990s. They're the perfect ID and OD to fit little jobs like this.
The derailleur pulleys were quite worn. That would cause sloppy shifting and provide space for random jingling noises from the chain. I scavenged an old Bullseye pulley and an off-brand alloy pulley from old Campy derailleurs in my bin of potentially useful items.
The ninja throwing star on the right used to look like the plump and healthy derailleur pulley on the left, several thousand miles ago.
The nice thing is, shifting in friction I don't have to worry about micro-millimetric perfection. It just has to line up pretty well. I get a lot of care-free miles out of my primitive junk.