[gregb]

I just finished one of these radios and I had the exact same problems, it sure seemed like the tuning cap was rubbing. It ended being the 1R5 tube socket was causing some kind of a problem. I tried cleaning it with a slight improvement but it did not fix the problem. I found that if I pushed down on the tube with a bit of pressure it would work fine. So I ended up replacing the socket and it works perfectly now. I examined the old socket under a magnifying glass and could not see any problem but the replacement works perfectly. This may not be your problem at all but it fixed mine.

Gregb