I just found this in a WPC game that has squeaky clean boards, NVRAM fitted, stored in an insulated office room heated at 20C 45% humidity (UK) & it’s actually quite a new display (2yrs?). Also checked TZ's display, which was bought at the same time, and it's also showing signs around the USB port.
I have contacted ColorDMD for help, because i can't explain this one. Will update if i hear back.
Has anyone else experienced this? I'll be checking all my games with these displays in - all 8 of them!
IMG_8258.JPGTZ display.JPG