John, as all the bands have pretty low power levels, it might be worthy having a look at the output transformer (T501, he binocular one) for shorts or scratched enamel or poor soldered joints. I would also have a look at the inductors in the LPFs, as I had a similar issue on 20m which boiled down to the enamel on one of the two ends of the inductor not having been removed properly. Resoldering the joint did the trick.
My2Cents
72/73 de Enzo M0KTZ
