[Electronic M]

CRT base appears to be a euro tube connector...I once was at a swapmeet where someone had some really old Brittish or German tubes with that style of connector...Some had a different number of 'pins'. I had the same impression when I saw them there for the first time...

In your shoes if I did not much like the set, badly wanted/needed service convenience, or had a situation where the wiring to the interconnects was damaged or otherwise unoriginal I'd be tempted to cut the harnesses and insert some other connector that I could easily make (or use an existent) extender for...In any case it's your set, your back/knees, your call.