I ring tested the yoke with a Sencore LC101. If the yoke is good it's supposed to give 10 rings or more. I got 9 max. Not definitive.
The DC resistance is supposed to be 36 ohms. I measured 47 ohms. The yoke is a bit different in that the horizontal windings are in parallel. This would mean that each coil should be 72 ohms. If I assume the difference is due to one coil, then it would have a resistance of about 135 ohms. Quite a bit different.
I swapped the horizontal leads and while the raster reversed, the focus problem remained on the same side. This, along with trying to rotate the focus magnet and moving to different positions has no effect on the problem leads me to believe that the yoke has a problem.
Another clue is that it appears that someone replaced on of the horizontal leads with HV wire. It has a polyethylene core and a plastic jacket. All the other leads are fabric coated.
Normal
Reversed
The ringing is probably due to the long jumpers I used to connect the yoke.
Notice that the keystoning is the same for both. If it was a supply issue it should be reversed when I reversed the leads.
It looks like I need to search for a yoke.
I would need a Sylvania 100-0001 or a 100-0002 and a horizontal choke 241-0002. The second version has a center tapped yoke instead of parallel windings and thus needs a center-tapped choke. I'd call it a transformer, but they call it a choke.
The Merit numbers would be MD-13 for the yoke and C-2980 for the choke.
If anyone can provide Thordarson or other cross reference numbers that would be great. The actual parts would be even better!
John