As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE COPILOT WINDOW IS VERY DIFFICULT TO OPEN AND CLOSE. FEELS LIKE SOMETHING IS BINDING IN THE TRACK. GROUNDED-YES. FOUND FWD LOWER SPECIAL BOLT BACKING OFF. RETIGHTENED LOWER SPECIAL BOLT, REF APPLICABLE STEPS OF B737-900 AMM TASK 56-12-11-820-80. NO ADJUSTMENTS NECESSARY. OPS TEST OF WINDOW HEAT GOOD.