While a ball sits in a kickout hole, higher-numbered switches in the same column stop registering; with the hole empty they work.
A ball resting on one switch stops others in its column
Cause: A failing 4049 row input chip (IC16 for rows 5-8 in the reported Firepower case), even though diodes and the jumper test check out.
Checks
- Check switch diodes for shorts first.
Fix
- Replace the 4049 for the affected rows.
Systems
Related tips
- Switch matrix connector pins and their chips
- Display board chips shown as 4050 are really 4049
- Segment missing or stuck only on certain characters
- Switches stuck on: board or playfield?
- Leon test: switch column drives (2J2)
- Switch matrix column test at 2J2 with Leon's code
- Whole game dead after working on a flipper EOS switch
- Board or playfield? The switch test jumper method
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)