Sounds like you've narrowed it down to the display. So replace it and move on.

The color DMD is amazing on Judge Dredd, Im just saying.

Could still be cables. My Congo was picky about cables after a new mpu and board work. Ones I got from pbl did not work as well from ones I got from great plains electronics for a different game. If you can, I would try swapping cables from different games and just see if anything changes. You could also swap the display into another game to know for sure if display bad.

I would try the DMD in another game, which does sound like it is the problem. I cannot see this being cold solder. I suspect but one of those 4 sided parts, which is not easy to change, if this does confirm to be the DMD in another game.

ColorDMD is still out of stock so that's not really a solution at this point. Just have to keep diagnosing the issue. Using another panel would help eliminate problems.

Could be a bad chip or component on the display panel. Unless it's a Vishay or Dale DMD, you're basically on your own.

For replacements, PBR has them for $168.85, and pinballlife for $179.95. Those are probably the least expensive new ones. Used ones pop up occasionally from folks who have installed colorDMDs.