1978 Ski-Doo Shop Manual, Page 35Get this manual
SECTION 02 SUB-SECTION 02 (DRIVE BELT)
5Belt sides worn concave1'1)6Belt desintegration
CAUSE a) Rough or scratched pulley surfacesb) Unspecified type of belt
REMEDY a) Repair or replaceb) Replace belt with correct Bombardier belt
CAUSE a) Excessive belt speed
REMEDY a) Using unspecified type of beltReplace belt with proper type of beltb) Clean pulley surfaces with fine emery cloth and lubricate with low temperature greaseInstall specified sprocket (correct gear ratio),
7Belt edge cord breakage
b) Oil on pulley surfaces