[Chas]

Contact Mark Oppat: http://www.oldradioparts.net/controls.html

If he has not got an OEM pot, it can be assembled from Centralab, Clarostat, IRC, Mallory

If Mark doesn't have it, you don't need it...

The type of pot on which I was going to attempt repair is the '30s design with no sliding contact directly on the track - a strip of sprung steel matching the track is pressed from behind by the wiper. Presumably this was to avoid/reduce wear of the then fragile track print.

I'm familiar with this pot. It is intended for circuits in which a very small current flow, known as "noiseless". It cannot be cleaned as the contact disk gets in the way. When "sprayed", the carbon deposit washes away with any solvent.

This pot is OEM in the National SW-3 as the regenerative control...

Do not be put off by the cost... I have known Mark for too many years, back in the '70's he was buying up control stocks, he was not wrong. Cannot even begin to imagine how many controls he has in stock... Having to maintain the inventory in a logical manner.

Chas