Nice sets, I think the hole on the left shouldn't be there though.

I rebuilt one of these last year for someone and they are an interesting set, it doesn't use a Flyback transformer, instead it has an oscillator type HV system like the electrostatics, it also has a very strange slug type tuner with a weird linkage system.

http://cgi.ebay.com/ANTIQUE-Raytheon-Belmont-Television-TV-A-10DX24-1948_W0QQitemZ220348812816QQcmdZViewItemQQptZVinta ge_Electronics_R2?hash=item220348812816&_trksid=p3286.c0.m14&_trkparms=66%3A2|65%3A10|39%3A1|240%3A1318

The oscillator HV is unusual but it gets more bizarre. In one of the pics you can see a 50B5 tube so marked on the chassis. There are actually three of them lined up in a row at that spot and behind them is a rectifier. The 50B5s are connected in parallel as horizontal output! The tube behind them is the damper--a 35Z5GT. Craziness. I love it.

Looking at the tube layout in one of the pics, it appears there are TWO 35Z5s in this set.

Right you are, immediately to the left of the damper is a second 35Z5 which provides the B+ boost.

An attempt at using more common radio tubes to ease replacement maybe?