the flow chart is to get a gun..
the polo's are cursed.. i went through hell with these to year their respect.
there are all sorts of problems that can go wrong.. had one working perfect after a rebuild.
then the image would wooosh woosh wooh, in and out like the power was being cut.. then sometimes startup voltage would be a wopping 250vdc kiling both the hot and the fragile vertical deflection ic's.. turned out to be the two diodes tied right into the mosfet that pulsed the switching transformer.. unreal.. of course the diodes looked good with the simple diode test.
I know this isnt what you wanted to hear, i think randy might have put together a flow chart for the polo.. i could be wrong.. might the mtc9000 he only did.
good luck, they can have anything from open traces, resistors, poly caps, corrupt hot, diodes, shorted coils, you name it.