I finally got around to swapping the yoke. Guess what, it was the yoke that was causing the focus issue!
I'll post some photos as soon as I get it finalized. In spite of being careful I managed to swap the two horizontal leads. I left them long in case I did something stupid like that. There's a bit of ringing that I hope clears up when I dress the leads.
The yoke that was in the set is the wrong yoke. It was a 100-0002 and the manual says that you cannot use it with an output choke that isn't center tapped without danger of breakdown in the yoke. That must be what happened to it. The manual warns that servicemen have been replacing the 100-0001 with the 100-0002 when they shouldn't.
The yoke I put in though is made just like the 100-0002. Moyer said that RAM says it can be used for either yoke. It came wired as though it was a 100-0001, but internally it's like the -0002.
Does anyone have a RAM catalog? I'd be interested in knowing what it says about a Y70F25 yoke. It's to replace a 100-0001 yoke in a 1-108 sylvania chassis.
I'd feel better about using it if I could find a center tapped choke to go along with it. Can anyone tell me cross reference numbers for a 241-0002 choke for this set? I've yet to figure out why they call it a choke instead of a transformer.
John