1970-1979 Ski-Doo Snowmobiles Service Manual, Page 138Get this manual
POWER TRAIN gap is present between end of chaincase flange and oil sealcOn 1970 models, adjust tensioner for Y4 in(6.4mm) chain deflection measured through chaincaseinspectionhole (Figure22)dPerform Pulley AlignmentePerform Brake Adjustment and Track Tension Adjustment as outlined in Chapter TwofAdd approved chaincase oil until level is flush with chaincase plugSee Chapter TwoAluminum Chaincase (With Automatic Chain Tensioner) RemovalInstallation 1Remove driven pulley2Release track tension (Chapter Two)3Pry out drive axle oil seal from chaincase with small screwdriver (Figure 27)4Remove cotter pin and spacer securing lower sprocket (Figure 30)Remove lower sprocket and chain 131