Edmund H. Ramm wrote:

But to get back to the purpose of this newsgroup: Are capacity losses,
e.g. down to 17pF from 50pF, in 50 years old moulded mica condensers a
common failure?

73, Eddi ._._.

I hesitate to say "common" but yes.

Often that failure is caused by the op twisting the cap over while in
place to see whats written on the other side. In American-made molded
micas this often causes the lead to break free from the molding and the
twisting action breaks away a few of the foil connections. Or worse,
twists them into a shorted condition.

-Bill