Check with Mark Oppat:  https://oldradioparts.net/

I think he is like Bill Perry and connectors, but in his case, he bought up all the pots,  Clarostat, IRC, etc.  Might be a bit pricey, but when you gotta have it you gotta have it.  Only place I know to get the RF gain pot for an HQ170/180, something like 1 meg on the same shaft with 5K.

Charlie