RCA 21CT55 #8802897 is Dead

[Tomcomm]

doogie812.........The FBX I'm using was intended to have the EHV rect on the top of its HV doughnut. Any loose fit would produce a continuous arc that could take the FBX out. The CTC2B FBX had a HV lead and tube cap. I cleaned all the HV grease out and removed the little hooky spring. I then quickly soldered a tined spot on the large output contact area and tack soldered a EHV rated lead wire and cap going to the original EHV rectifier. I then completely filled the output cap cavity with RTV silicon. Works fine, but at an occational 40+kv non loaded run with no 6BK4 reg the little 3A2 EHV rect arcs across its full 2in length. Im using my original 21FBP22A rare-earth gray screen I installed in place of the 21AXP22 in '64. This is the last and IMHO the best roundy CRT. RCA rates it's ultor at 27.5kv and their data sheet states "Brilliance and definition decrease with decreasing ultor voltage".