Zenith Royal 2000 on-off switch.

[zeno]

Not sure if it would have applied here but Malory used to sell
two different P-P replacements. They were the KR8M & KR9M
IIRC. All you did was bend back the tabs on the pot, slide it
in place then drop a bit of solder on it to keep it from turning.
Very rugged, easy & cheep. We went through tons of them &
never had one fail.........

73 Zeno
LFOD !