Welcome to pinball ownership & Pinside
Are you talking about players 3 & 4 scoring displays ? many time most of the digits don't work ?
I think you have posted in the correct boards here on Pinside, but you may perhaps also search and post in the "6803" club thread : https://pinside.com/pinball/forum/topic/bally-6803-club-all-welcome and-or- the Dungeons & Dragons thread : https://pinside.com/pinball/forum/topic/official-dungeons-and-dragons-dd-club-all-welcome
Someone linked in the 6803 thread "Clay's guide" http://www.pinrepair.com/6803/ , if you re-seat connectors do it with the power off especially if it's the displays
I'm hoping someone with most firsthand knowledge will comment further