What was found
FO'S SIDE WINDOW IS VERY HARD TO OPEN AND CLOSE. GROUNDED - YES. REMOVED FO'S SLIDING WINDOW. FOUND FWD LOWER TRACK ROLLER LOOSE. REMOVED AND INSP FOUND NO DAMAGE. REINSTALLED ROLLER AND SECURED WITH SET SCREW. REINSTALLED WINDOW, OPS GOOD. REF B737-900 AMM 56-12-11-000-400-801, NO ADJ REQ.