[Tubesforme]

Just an idea if you haven't tried yet. Poke around the under chassis with wood dowel or something similar when problem occurs. Might have a bad solder joint somewhere.

Been there, done that! In fact I have resoldered all of the chassis grounds and all of the capacitor blocks that I rebuilt. I have the chassis out of the cabinet and not a single voltage varies, on anything when I probe and pull on the connections. I have even tightened up the tube socket contacts and hand cleaned them.

This doesn't happen when I have my signal tracer connected to the chassis so am thinking I need the chassis ground and being this is a TRF set, need a longer aerial. I noticed the position and direction of the 20' wire I am using does make major changes. A problem is in Los Angeles, we have far too many stations and they will leak over one another on a TRF chassis. My model 70 works just fine.

None of this, however, explains why the volume control seems to get noisy so quickly.
Thanks