Actually, I found a solution for my problem, and it literally makes
no sense. I'm posting it here in the hopes that someone could explain what's going on.
If you recall, I mentioned that
increasing the XRGB's sync level made the sync problems worse. This was using retro_console_accessories Boosted Sync cable. Turning the Sync from 'Auto' to 'Off' helped a lot, but it didn't get rid of every sync problem.
I had also rewired the JP21-XRGB adapter that came with the Mini to Euro SCART. I realised a little bit ago that, while I'd tested it with the Mini's sync on 'Auto', I'd never turned the Sync
off. Having the Mini's sync off with the unboosted sync adapter fixed every problem.
To me, that makes absolutely no sense whatsoever. Why would I get sync problems from BOOSTING the sync signal? Is there even such a thing as 'too much sync'? I have noticed that, on the Mini's upper end of the Sync adjust, that the picture would start to move to the left one pixel at a time per one increment on the Sync adjust, starting around a level of 23 or so, until it lost the picture somewhere around 28-30.
I'm happy that my problem has been resolved, now I just want to know what the hell is going on.
"Thanks for the nice reply. I do offer to do work without hot glue too if people prefer it that way." - Drakon