Help needed with a "19 Zenith 9-291 chassis (SB1923W Space Command set, 1985 build)

[>QUAD<]

Hello

This is my first post on the VideoKarma forums, I have been posting on AudioKarma in the past but never before here,
I've been browsing the forums on here quite a few times though.

So, a buddy of mine picked up this "19 Zenith Space Command set (model SB1923W) from a Goodwill this December,
fascinated by "how cool things would look on a retro CRT set", and a short while later
(when the fascination went away and he went back to his "40 flat panel) he passed the Zenith to me.

While checking it out at his place I was surprised that the image on the set was quite good and the CRT still looking strong,
although the set did need some adjustments (focus, bit of convergence, minor color adjustment, yoke angle, and horiz. width).

Having done most of the things I just mentioned, I am now left with the overly wide picture, for which there is obviously no adjustment.
Suspecting the B+ being out of range, I went through the power supply board and measured the B+ at what appears to be 116V,
I have looked at all of the resistors on the power supply board
to see if any have drifted, and all look fine (the sand blocks are all still within %5 at worst),
there was one resistor that was marked 19K (by the color bars) sitting across the filter cap that drifted to 16.8k but replacing it didn't help.
Electrolytics on PS board all test fine.
The power supply module uses the STR (TO-3 type) power regulator.
The set doesn't appear to have had any service done to it except for one service sticker on the back dating to '86.

So, is anyone familiar with this chassis? I tried looking it up on google, and managed to find a list of models that use this chassis
(oddly enough my set isn't mentioned in that list), but not much useful info other than that.

If anyone has the schematics diagram, or is willing to help me get this set working as it should, I would really appreciate that.
I am going to keep it, upgrading a 1982 "13 Hitachi set I have right now (won't be getting rid of the Hitachi either,
but I would love to have a bigger screen to enjoy my recently acquired NES on )

Here are a few pics, the set is in quite a nice shape, with only a couple of small scuffs overall,
the inside was very dusty but looks great now after a thorough cleaning.