Bad Micas?

[Eric H]

I've been working on this Tele-Tone Porthole for the last couple months, finally got it recapped and replaced some out of spec resistors.

It plays pretty well but I'm having one last problem and I'm thinking it could be some bad Micas in the Horiz circuit.

It'll play fine for a while then it starts to tear at the left edge, sometimes it flops over completely or tears so bad it's unwatchable.

This is basically a 621/721 chassis, it has three trimmers on the back of the chassis for Horiz Drive, Frequency and Locking Range.

There are Micas connected to the trimmers so I'm suspecting they could be the problem?

Pic 1 is working normally, pic 2 shows the tearing.