Alright, I had some extra time today, so I thought I might as well give this a shot.
So here's the problem monitor shortly after turning it on:
When this pic was taken both horizontal and vertical size were at their lowest setting on the remote. If you give it an hour both the top and bottom will stretch horizontally way past the edges of the screen leaving only the center narrow. Like I said, I swapped absolutely everything on this chassis and nothing made a difference. There's just the flyback left to swap.
Time to break out the desoldering gun. 10 minutes later the flyback was out. Out with the old, in with the new:
Original flyback left, HR Diemen 46274 on the right.
The new flyback comes with instructions to jump some pads:
So I did just that:
Notice the missing resistor R447 at the bottom right. The original 33kohm resistor was supposed to be replaced by a 68k one according
the instructions in the Neo-Arcadia thread, however, the pics in that thread show that the image is pinched in on the left hand side. Grantspain recommended a 47k or 56k resistor in
this thread on Arcade-Otaku. Resistors are cheap, so I bought all three.
Soldered the leads to the neckboard:
Thicker lead goes under the cap of the neck connector, thinner lead next to the connector.
I first soldered in the smallest resistor, 47k. Connected the chassis to the tube and flipped the switch. Thankfully no smoke and no bang. Turned up the voltage on the flyback to get a bright image. Geometry looks great. Image is a small square in the middle of the screen, which is what it's supposed to be because I still have the horizontal and vertical size pots at their minimum setting. Adjusted those to get a full size image. Unfortunately, there's an issue. Both the top and bottom of the screen have a shimmering effect. 47k is no go.
Took out the chassis and swapped in the 56k resistor. Turned it on and image is now visibly larger. Turned down the horizontal and vertical size pots. No shimmering anymore! I played around with the focus pot on the flyback, however, I couldn't get it pin sharp. It looks OK, but visibly soft.
Anyway, it's good enough for now. I'll mess with the yoke rings and try to get it looking better at a later time.