I'm thinking of buying this Admiral

[Electronic M]

On wire wound pots (cough rheostats cough) you can often bridge the open and get the pot usable again.

In that rheostats case, you may need to add series resistance (given a lot of turns look bad) and reverse the ends of the pot so the wiper/rotor does not rest in the bad zone when focus is adjusted. Necessity (or cheapness and poor parts availability) is the mother of invention (but does it have Zappa too?).