Zenith 25MC32 problem

[sgtrob]

Hello Everyone! I put my Zenith 25CC50 with flickering vertical off to the side, to tackle another set. I am working on a Zenith 25MC32 round screen color set I bought at a yard sale in 1993 for $5. I just now fired it up, and the problem is, there is no vertical, just a horizontal line. BUT, I unplugged the convergence assembly and the veritcal came back!! I plugged it back in, and it went away again, unplugged it, it came back you know the rest. this makes absolutely no sense, unless there is a short somewhere. But where? Does anyone have any ideas? ALSO, there is a small flat metal door on the bottom of set that is used to hide some knobs. Anyone know where I can find this part, or can spare another one? I think the set is is of a 1964-65 vintage. Thanks!