The wire type fuses act like a big resistor. Check the voltage drop and how hot the 300ma fuse gets in the cathode circuit. The chemical fuses have less resistance and a much tighter open threshold.
Those flybacks always seem to fail due to arcing in the secondary near where the rectifier sticks in the top of the fly. Probably due to all the heat.
Set the cathode current for minimum at full brightness.
Set the HV for 25kv at minimum brightness.
Check the drop accross the 1k cathode resistor on the shunt tube, if it exceeds 1 volt increase the hv untill you get to 1volt, check the HV again if it exceeds 27kv increase the HOT screen resistors value.
If the shunt tube resistor drop is less than one volt turn the efficiency coil clockwise until you get 1 volt drop staying under 220ma HOT cathode current.
If you are worried about X-rays set your target for 24kv at minimum brightness. You wont really notice it except on a weak crt although most likely you will have to increase the screen resistor to get the shunt tubes loading within spec.
Lowering HOT screen voltage reduces drive/hv/hot cathode current, turning efficiency coil clockwise increases it.
It a bit of a balancing act.
On the capacitors.
Hour usage has little if nothing to do with it. Davewm has a NOS Packard Bell he has the same issue with. I also have several NOS PBs with the lossy caps.
The only way to test this fault in the caps is an old school eye type tester. The eye wont open all the way with a lossy orange/red/brown drop.
It also appears to have allot to do with the circuit they are in. They drive the Vertical circuit nuts.
The symptoms are: poor deflection/linearity, one of the size controls at max, drift/size change with temperature/warmup, poor stability, having to adjust hold controls during warmup
It could just be the supplier rca and pb used in the late 60s. I dont remember running into this with Zenith or other sets.
Some of the caps
