[Electronic M]

If you don't know where the arc is fixing it can be extremely difficult. Sometimes it is worth while to get it to repeat to find it.

Cleaning the dust inside the HV cage is a good start, but don't go crazy on the flyback...if you break a lead off the fly it can be game over for the set.

The front of the shroud tends to stay fairly clean inside, but the area near the yoke can get fairly grimey...if it's arcing in the shroud the yoke end is where I would first look.

The 21AXP is designed t run at 25KV and the weak HV system of a CTC5 is having a really good day if it can deliver 20 with the pull down regulator unplugged....The HV cannot not shoot up to 100KV and saw the neck off the CRT like a Zenith CCII with bad safety caps so the CRT shouldn't be harmed. Flybacks can also take around 10 seconds of arcing (especially when cool) and be okay.