[Texasrocker]

Have you tried swapping out the Rectifier tube? Internal intermittent rectifier tube plate shorts possible? Not usually the prob tho, without the tubes giving a spectacular light-show.The 25-50 cycle power- trans will work on 60 cycles, but generally always run hot in my past experiences. Whenever I run across these sets, I always replace the 25-50 cycle ac trans with similar type 60 cycle trans I rob from other cheap parts sets as they come avail. I would suspect the power trans in your case(s)?
I remember I bought a couple nice TV sets many yrs ago for cheap at a garage sale ( without close inspection) of the mains, that never worked right. After closer inspection, I had purchased 2 TVs that had 50 cycle ac trans mfd in Mexico,for Mexico 50 cycle pwr mains, and although they worked, the "picture" was never clear & audio was distorted.Their lifespan was short also on 60 hz mains! Both ended up with smoked power trans & blown fuses. I have run across several old Canadian model Philcos with the 25-40 cycle trans that were previously totally-fried, windings internally by someone previous plugging them in using modern day 60 cycles mains due to internal excess heat inside the trans. Limiting incoming ac line voltage keeps these 25-50 cycle trans from smoking, for awhile, but its better to rid them if possible and replace them with other vintage 60 cycle types when possible.