The first ball is served, but the next ball never leaves the outhole, and a ball in the top right saucer stays there.

Outhole and saucer won't kick out: cracked joints on the driver board pins

Cause: Cracked solder joints on the driver board header pins feeding those solenoids.

Checks

• Fire the outhole and saucer coils in solenoid test.
• Remove the driver board and inspect the header pins for those solenoid circuits for ring cracks.

Fix

• Reflow the header pins on the driver board (ideally replace the old headers and repin the connectors).

Systems

• Williams System 4

Games

• Laser Ball

Related tips

• Burnt 27 ohm lamp matrix resistors R149-R156 on the driver board
• Physically blown 7408 on the driver board
• Solenoid fuse blows at power-on and solenoids fire: driver board logic chips
• Slings and pops all burned at once: CPU lock-up from the 40-pin interconnect
• Driver board transistors and what they drive
• Test a 2N4401 pre-driver with a meter
• Leon's code with the driver board attached
• Add a blanking LED to a driver board

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