Tim Shoppa wrote:


Others tell me this is well-known but I still don't have any
understanding
of why metal would shrink or grow with time.

Tim N3QE

Where there's pot metal involved it certainly swells up. Thats a
scourge in 1920s sets that use pot metal pulleys, brackets and capacitor
frames. My understanding is that it is due to reaction/corrosion
between the various metals in the 'pot' mix.

-Bill