Capehart 661-P

[old_coot88]

Phil,
Regarding the width sleeve, it shouldn't matter if it's copper/brass or even alumunum, long as it's non-ferrous metal. Also, i don't recall it ever being necessary for the ends to lap. Some sleeves were completely clad with insulation on both sides, so the ends never made electrical contact anyway.
On that slight bloomy-shrinky thing it's doing, one's first thought would be a HV problem and a weak HV rectifier. But it's not doing what it'd do if that were the case. The pic is expanding with increasing brightness and shrinking when brightness is lowered, the opposite of what you'd see with a weak rectifier.
It's almost as if there were a designed-in coupling between the brightness control and the 6L6, controlling its gain. But i can't see any evidence of that in what's decipherable from the schematic.
(I must be a dummy, but can't seem to find any 'schematics' link in that website posted by Earlyfilm.)
oc