What was found
DTW - FLT 3631 - AT ALTITUDE THE MANUAL TRIM WHEEL SEEMS TO FREEZE, YOU CAN''T TRIM THE ELEVATOR WHEN THIS HAPPENS. DID NOT FLY THROUGH ANY CLOUDS OR PRECIPATION, STARTED WORKING AGAIN ON DESCENT AT 6,000 FT. MAINTENANCE REMOVED PANELS FOR HORIZONTAL TRIM, DRIED, CLEANED AND LUBED TRIM MECHANISMS. ALL CHECKS GOOD. (M)