Reducing Image Width on Tovis Vision Pro MTG-1901CN

[DJilla]

I'm having issues reducing horizontal width on my Tovis Vision Pro MTG-1901CN monitor with my Neo Geo 1 slot unit (MV-1FZ). The horizontal width potentiometer on the remote board stops shrinking the horizontal image about half way through rotation range, I initially though it was an issue with the potentiometer, but I replaced it with an identical part and there was no change.  The tube itself is a Samsung A48KRD82X, which I replaced the original broken tube with and I recently recapped the monitor with a cap kit from Bob Roberts (oddly enough I was left over with two caps: one for C413, which wasn't occupied on the board and one just labeled "?").

Basically, I'm left with the image extending ~.75" past both edges of the screen and I'm wondering what my best course of action should be? I'm thinking about ordering a width cap kit from Bob, but was wondering if it could be something else at fault.