Panasonic CT-1310M keeps blowing horizontal output transistor

[vol.2]

At this point, I wouldn't be surprised if there wasn't a hard-to-see break in the PCB or something. PCBs can get brittle with age, and a drop or a jostle (like from being taking out of storage and put on the side of the road) can cause little fractures

Usually the best way to stumble upon such an issue is by following voltages. if you get the right voltage at one end of a supply, and then you follow it along the trace to components, you will often find a break in the PCB by finding it not where it is supposed to be

It's kind of like doing a Sudoku and figuring out a row or box by omission

Of course it's not for sure, but it's one thing you could do if you're feeling stuck (follow all voltages from their supplies)