Holding the left button, the small upper left flipper fires three or four times and then falls back, while the lower left flipper holds normally.

Small upper flipper fires repeatedly and drops: EOS contact tension

Cause: An end-of-stroke switch that looked closed but had too little blade tension, so it didn't make reliable contact.

Checks

• Check every EOS on the left side for contact pressure, not just the gap.
• Make sure the lower flipper's EOS opens before the switch that brings in the upper flipper closes.

Fix

• Re-tension the EOS blades so they close firmly.

Systems

• Bally MPU AS-2518-35

Games

• Paragon

Related tips

• GI dims whenever the left flipper button is held: upper left flipper EOS not opening
• Upper flipper weak and won't hold: second leaf switch on the lower flipper not touching
• Both right flippers dead, left works: wire at a coil lug not making contact
• Two upper flippers die after cleaning EOS switches: readjust the break-make pairs
• Upper flipper flutters, then dies: pitted EOS contacts
• Flipper won't kick but holds if lifted by hand: dirty or worn EOS switch
• Flipper sometimes ignores the first button press: replace the EOS switch
• Flipper machine-guns when the button is held

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