There is a fuse inside the unit on one of the boards. It supplies 12v to the horizontal oscillator. If your flyback is bad, that fuse will blow and you will have no display on the CRT. The board is accessible from the bottom so you will have to flip the unit onto its side to access it. I took my flyback out and ring tested it to verify. It failed. I think a good one has around 300 ohms DCR on the HV winding with smaller and smaller values as you move down the taps from the HV to the bottom. My bad one checked around a meg or more.?
