[Arran]

Speaking of the tuning condenser, I had one once where the set behaved intermittently, there was one section of the dial where you could hear scratching noises, and the reception pop in and out, sort of a dead spot. Naturally I thought, must be bent plates, so I inspected the outside plates of of each section of the rotor, found a few places where it looked too close, gently bent them with the aid of a pallet knife. It worked somewhat, but it still would cut out around the same area, but after handling it I noticed that the chassis, and the tuning condenser was dusty. So I took an artist's brush, and the shop vac to it with the crevice attachment, and vacuumed the top of the chassis, focusing on cleaning the dust out of the tuning condenser. That shop vac is powerful enough to such of chunks of wood, stones, etc., and it must have done the trick because the dead spot, popping, and scratchiness was gone. I'm not saying that is the problem here, but its another thing that can cause this, along with bad solder joints on grid cap leads, which are often attached to the tuning condenser as well.
Regards
Arran