Just fixed my first plasma TV.

[Zenith26kc20]

I usually find the x main or y main power supply shorted. They can be had on EBAY but after a few years, they start to eat parts.
I run my 42' LG without it's back for better cooling.
It's had three y main supplies. All go about a year and a half.
Leaving the back off stops the screw removal ritual!