[time-nuts] aging/failure of un-powered xtal oscillators?

[ed breya]

If there are plenty of them, I'd recommend dissecting one to see how 
well they're made, and what sort of components are inside. If the 
crystal is hermetically sealed, it's probably OK. If there are any 
aluminum electrolytic caps in there, they may be no good. Most other 
parts from that era should be OK.

If possible, you should pretest a bunch of them to see if they seem 
up to snuff.

Ed