What was found
DURING CLIMBOUT AT 5000 FT FORWARD ENTRY DOOR WARNING LIGHT ILLUMINATED. FORWARD ENTRY DOOR HANDLE WAS SECURE. TURNBACK TO LAS. MX ADJUSTED L-1 DOOR SENSOR. ACFT WAS PRESSURIZED TO 4 PSI, NO FAULTS WERE NOTED. DURING PRESSURIZATION SHOOK HANDLE, LIGHT REMAINED EXTINGUISHED. PROBLEM RETURNED NEXT FLT, LIGHT REMAINED ON DURING TAXI TO GATE. THE L-1 DOOR UPPER HINGE GUIDE ARM WAS ADJUSTED AND LIGHT EXTINGUISHED AND REMAINED OFF; LIGHT ILLUMINATED ONCE MORE AS ACFT TAXIED TO GATE ON RETURN FLIGHT TO LAS. TROUBLESHOT TO INTERMITTENT WIRING PROBLEM, PLACED ON MEL 52-03-19, COND 1. MX REMOVED & REPLACED L-1 DOOR INDICATION SENSOR S199, OPS CHECK GOOD.