I've got an old (1949) Zenith AM-FM set I'm restoring. It didn't need recapping:
mostly ceramic caps and the electrolytic and a 0.047 bumblebee had been recently replaced.

All that's bad are the volume and tone/power switch controls. The
tone control circuit is really really strange: it uses a 5 meg pot in
a feedback circuit, and the control only does something in the last 300K
of its range! It could be replaced with a 1 meg linear.

But the volume is odd: its a two meg pot with a tap at
an unknown spot, though its good enough to measure, which I will.

But ... where do I find replacement pots, even approximate ones,
for this beast? They are mechanically very ordinary ones,
similar to modern ones. One meg pots with a tap I can find,
but not two meg.

Doug McDonald

Try Mark Oppat.

http://www.oldradioparts.net/controls.html