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I did a little work on this tonight, replaced most of the paper caps on the front of the chassis (short one .1 and one .47) and checked the tubes in the tuner (already checked all the others) turns out both tuner tubes had shorts, a 6BC5 and a 6CQ8, I found a good used 6BC5 and a NOS 6GH8 to replace the 6CQ8, i also installed a new RCA 6DQ6 horizontal output tube, it had been replaced before with a Sylvania and it was tired, the Damper was very good.
It worked pretty much the same, the vertical would still drift after running awhile (though the horizontal was now stable), eventually reaching the end of the hold range so i started poking around on the PC board with a soldering iron, warming up the caps in the vertical circuit to see if any made a noticeable difference.
When I got to this .0047 Bumblebee (below) it started rolling faster.
Swapped it out with a fresh new cap (didn't have to remove the shield) and powered it up, the picture was now shorter and the hold is now stable right in the middle of the range.
Of all the caps in the set it had to be the Bumblebee that was causing the trouble!
I adjusted height and linearity and ran it for at least another hour and it never lost sync, sound is excellent on this set as well.
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