Westinghouse vertical roll

[nasadowsk]

It's a heat related issue - there's a component that gets warm and goes out of tolerance.

Get yourself a can of freeze spray. Or the 'canned air' at office stores. Turn it upside down.

You need chassis access here. Let the set run normally, until the problem appears. TURN THE SET OFF. The hit the suspect are with freeze spray. Try it again. If it's ok, let the problem re-appear. Repeat, but hit a smaller area (fewer components). Keep trying until you narrow it down to one component. Replace that one.

I had this with my Bendix a few months ago. It takes a bit of time, but once you find the bad part, you'll know it - because hitting it with spray ALWAYS fixes the problem for a while.