After cleaning and adjusting all the flipper EOS switches, the upper left playfield flipper and the lower left playfield flipper stop working while the others still work.

Two upper flippers die after cleaning EOS switches: readjust the break-make pairs

Cause: On games with stacked flippers, each lower flipper carries a double EOS switch: the inside contacts are the normal EOS and the outside contacts pass power on to the upper flipper. After cleaning, those switch pairs were no longer adjusted correctly.

Checks

• Push the flipper plunger in slowly by hand and watch the EOS stack: the inside contacts should open first, then the outside contacts should close (break before make).
• On Elektra the lower playfield flippers only work when the lower playfield is active, so use the flipper test to check them.

Fix

• Clean and readjust the EOS switches on the dead flippers so they break, then make, near the end of the stroke.

Systems

• Bally MPU AS-2518-35

Games

• Elektra

Related tips

• Upper flipper flutters, then dies: pitted EOS contacts
• Both right flippers dead, left works: wire at a coil lug not making contact
• GI dims whenever the left flipper button is held: upper left flipper EOS not opening
• Small upper flipper fires repeatedly and drops: EOS contact tension
• Upper flipper weak and won't hold: second leaf switch on the lower flipper not touching
• Solenoid fuse blows when a flipper is used: worn spacer in the EOS switch stack
• Flipper sometimes ignores the first button press: replace the EOS switch
• Flippers dead though fuses and EOS switches are good

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