1980 Ski-Doo Shop Manual, Page 224Get this manual
SECTION 05 SUB-SECTION 02 (DRIVE BELT)
Open the driven pulley by twisting and pushing the sliding halfHold in fully open position
Slip the belt out from the drive pulley
Slip the belt over the top edge of the sliding halfLift the countershaft upward approximately 50 mm (2 in and slip the belt between the shaft and the bearing cage
WARNING: It may be necessary to loosen the brake adjustment in order to easily lift the countershaftAlways check that the brake disc is correctly installed between the brake pads and that the brake is well adjusted+