The 4th digit from the right is the only one working on my 6 digit display.

Swapped out a 7 digit and it was fine, so it's not the signal or harness. Also put that display on a 7 digit harness, and still just the one digit working.

Considering swapping out the 14543 as I can't see any one component that may impact the other 5 digits and find it hard to believe something in each of those circuits has gone but not in that one circuit.

Reflowed entire display, too.

Suggestions? TIA

Thanks, but it was this - never would have considered this, glad I found it!

Removed the two transistors for #4 and the rest fired up. Moved the two transistors from #6 (not used in Medusa) to #4 now all good!

https://web.archive.org/web/20161201081113/http://stevekulpa.net/pinball/bally_disp6r.htm

"One digit is very bright, and the rest are out

I which I could remember the name of the guy that told me this, but I can't - sorry. Anyways, if you have one digit that's very bright and all the rest are out, simply replace the digit driver and level shifter transistors for that digit. Turns out sometimes a short transistor will draw so much current that there's not enough left to drive the remaining digits, and so they all go blank. Just use the chart above to determine which transistors to replace. "