That's good to know- always learning something new here. What about fingerprints though? It looks like they have been there for quite some time since the tarnish has happened between the oil from the print.. If that isn't going to make any difference I will just leave it alone.
I don't know. Of course you could just leave it, fix all other problems and get the unit working, *then* decide if the discoloration is worth pursuing. Maybe the output frequency will track the dials well, and if so, who cares about surface color of interior things you can't see?
Or you may find it's unrepairable (dead unobtainium valve?) in which case the tarnish is also moot.
I do have all of the pieces of the shaft and have contemplated just gluing or epoxying them back together, but the biggest problem with that is that I don't think I can get the pieces out of their seats without totally shattering them. I have them soaking in PB blaster at the moment to try and get them loose, but one of the lock ring pieces is made of brass, so a penetrating fluid is unlikely to do much for that one. Aside from using a torch to expand the metal pieces to retrieve the mycalex in whole, I don't know what I can do.
So, they are held in by more than just the grub screws I can see in the collars? They are glued in as well?
Wow, that sucks.
One possibility might be to press the pieces out. Can do even with just a bench vice. But if the pieces have irregular broken ends that's a problem. You don't want to damage those fracture surfaces, since to glue them they must fit exactly with the mating fracture face.
Could you make a jig to glue the pieces together while still in their respective collars and parts?
Bearing in mind that then the dial will probably be out of cal a bit.
Sorry, I forget - did you consider using fiberglass rod? It comes in all sizes, and every company that sells electrical insulating materials will stock it. It's extremely rigid, but I don't know how much worse its high frequency dielectric parameters would be compared to the Mycalex.