On every score display and the credit display, the digits 4, 5, 6 and 7 appear as 0, 1, 2 and 3, while 0-3, 8 and 9 are correct.

Every display shows 0-3 where 4-7 should be: a missing data bit in the display ribbon

Cause: One bit of the BCD display data (bit 2) was not getting through: the ribbon cable between the MPU and the display boards was at fault.

Checks

• Because every display is affected the same way, look at the MPU side and its cable rather than the displays.
• In display test, check the data line for that bit with a logic probe for activity.

Fix

• Repair or replace the MPU-to-display ribbon cable.

Games

• Space Riders

Source: Pinball Repair help group!! (Facebook group)