What was found
JFK/SDQ - FLT 79 - AIR TURN BACK. DURING CRUISE AT 330, DOOR LIGHT ON MWP FOLLOWED SHORTLY BY CABIN DOOR LIGHT L4 INDICATION ON SECOND OFFICER DOOR PANEL, THE MECHANICAL RED/GREEN INDICATION ON DOOR WAS PART WAY BETWEEN RED AND GREEN. DECISION WAS MADE TO RETURN TO JFK. INSPECTED L4 DOOR LOCKING MECHANISM IAW AMM 52-10-20. FOUND VISUAL INDICATOR OUT OF ADJUSTMENT. ADJUSTED VISUAL INDICATOR WINDOW AND 25WS DOOR INDICATION SWITCH IAW AMM 52-10-11, PAGE 501. DOOR LOCKING AND INDICATION SYSTEM OPERATION CHECK NORMAL PER AMM 52-10-11. AIRCRAFT RETURNED TO SERVICE. (X)