The failure modes I have seen were
1) loud hum pops breaker. Dead shorted.
2) Runs hot, pops breaker after running a while.
3) pix pulsates with scene change. Open / ing.
I probably did a dozen of them from when new up to
the early 90's after that most got junked ( for no good reason).
And that was working on thousands of them.
I have seen quite a few bad ones on the forums lately.
Bottom line is GE ( made most of them) never expected or wanted
them to last 40-50 years ! That is overkill......
Test is easy. Unhook one end & see what happens current wise.
The only other thing I remember doing this was on REMOTE sets the
ON/OFF triac. That was rare. Other breaker pops were horz / HV related.
73 Zeno
LFOD !