What was found
ON FINAL APPROACH AROUND 2500 AGL, RECEIVED RT ENTRY DOOR EICAS. MESSAGE WENT AWAY ON TOUCHDOWN. CREW ENTRY DOOR INDICATION SYSTEM INOP. VERIFY THAT CREW DOOR IS CLOSED, LATCHED & LOCKED BEFORE EACH DEPARTURE. USE HAND SIGNALS OR VERBAL COMMUNICATIONS TO VERIFY SECURITY OF CREW DOOR WITH FLT CREW. BITE TEST PFD ACC FIM 32-09 FT813. DOOR SYS TEST CODE 502 , NO FAULT. WITH R1 DOOR CLOSED, CODE 090 TEST PFD, TARGET NEAR. TARGET FAR WHEN DOOR IN OPEN POSITION. VISUAL INSPECTION OF SENSOR/TARGET PFD SAT. PERFORMED PSEU BITE & FOUND CODE 090 RT NR 1 PAX DOOR LOCKED, INSPECTED DOOR SENSOR S10090 & FOUND JAM NUT & PLUNGER LOOSE, READJUSTED TARGET TO SENSOR GAP IAW AMM 52-71-00-5, TEST OK.