Have you tried cleaning fluid into the pot?
Servisol Aerosols
Top left. Gosh, that brings back some memories.
Failing that, most pots are just bog-standard items. One of the main things is whether or not its Linear or Log or Log Log, etc., resistive and physical size is obvious, and remember, cutting the shaft must be done by clamping the bit that's coming off, in the vice. Not holding by 'tother end.