[morzh]

Here's some other thoughts:

1. Often times if a tube goes bad a radio still receives station(s). If this tube is the 27, 1st det-amp, you may still hear station(s) but you won't have volume regulation. Check the tube (better yet - all ov'em).

2. Turn off your power, put one end of your Ohmmeter to the wiper of the pot (It has no active resistance in parallel, so you don't have to desolder nothing), and another and to the Chassis. Rotate the shaft and see the resistance going from 500K to 0. Repeat the same with the other Ohmmeter end at where the pot connects to the 18 and 19 caps together. Same thing only in the opposite direction.