[Arran]

Vlad;
I would tend to agree, I only suggested the loop antenna connections since he was already looking at the end of the radio. I would also suggest looking at the plate load resistor on the 1S5 tube, those can go up in value, if not go open circuit, the grid bias resistor on the 3S4 is another weak point. I was certain he mentioned checking them before, but sometimes components behave differently after voltage is applied, carbon composition resistors are notorious for this.
Regards
Arran