What was found
WHEN MLG WAS SELECTED TO RETRACT, MAINS RETRACTED & NOSEWHEEL DID NOT. REF EMERGENCY ABNORMAL PROCEDURES N2 & RETURNED FOR LANDING. PERFORMED A VISUAL INSP OF NLG UPLOCK SWITCH & NO DEFECTS. VERIFIED NLG UPLOCK SWITCH PROPERLY RIGGED IAW AMM 32-32-10, NO DEFECTS. PERFORMED OPS CHECK OF MLG RETRACTION & EXTENSION LAW AMM 32-30-00. OPS CHECK GOOD. BLED MLG SYS IAW AMM 32-00-00, NO DEFECTS. VERIFIED NLG STRUT PROPERLY SERVICED IAW AMM 12-10- 52, NO DEFECTS. VISUALLY INSP NLG SQUAT SWITCH & FOUND IT HAD A TEFLON WASHER INSTALLED BETWEEN PLUNGER & BODY WAS NOT ALLOWING SWITCH TO WORK PROPERLY. VERIFIED THROUGH AMM & AIPC & MCC THE TEFLON WASHER WAS NOT SUPPOSED TO BE INSTALLED ON THAT SWITCH. REMOVED TEFLON RING ON SWITCH AS REQUIRED & VISUALLY INSP SWITCH & DIDN`T FIND DAMAGE. PERFORMED OPS CHK OF MLG SYSTEM IAW AMM 32-30-00. OPS CHKD GOOD.