After coming across some shuffle bowler 6 digit displays, I was looking for info of how to test them in a williams 3-6 pin - with the hope of swapping the glass into a system 6 pinball. I found info for the 7 digit displays (ribbon cable) but my google fu turned up no info on testing the 6 digit edge connectors from a shuffle alley. The connectors are not the same pinout, so here is what I came up and I made a video:
Cleaner solution would be to use a blank edge connector (arcade suppliers sell them) instead of an old display board, but I was going for 'free' since I had no idea if any of the displays were good. Out of the five, three looked pretty good, one had minimal pimples, and the last was very pimply.