Craftsman 139.18057 Owner's Manual

9To avoid SERIOUS damage to garage door opener,use ONLY those bolts/fasteners mounted in the top ofthe opener.ASSEMBLY STEP 3Install the Idler Pulley• Lay the chain/cable beside the rail, as shown.Grasp the end with the cable loop and passapproximately 12" (30 cm) of cable through thewindow. Allow it to hang until Assembly Step 5.• Remove the tape from the idler pulley. The insidecenter should be pre-greased. If dry, regrease toensure proper operation.• Place the idler pulley into the window as shown.• Insert the idler bolt from the top through the railand pulley. Tighten with a 3/8" lock washer and nutunderneath the rail until the lock washer iscompressed.• Rotate the pulley to be sure it spins freely.• Insert a 1/4"-20x1-3/4 bolt into the trolley stop holein the front of the rail as shown. Tighten securelywith a 1/4"-20 lock nut.WARNINGCAUTIONMotor UnitSprocket"U" BracketLock NutBoltsSLIDE RAIL TO STOPSON TOP AND SIDESOF BRACKETCoverProtectionBolt HoleBoltHook Spreaderinto Back Slots,then Snap TabInto Front SlotIdlerPulleyGreaseInside Pulley3/8" LockWasher3/8" NutCable LoopIdlerBoltLocking PliersTrolleyStop HoleChain andCable Pulley RailBoltNutWasherTrolleyIdler PulleyTrolleyStop HoleBoltLock Nut1/4"-20Bolt 1/4"-20 x 1-3/4HARDWARE SHOWN ACTUAL SIZENut 3/8" Lock Washer 3/8"Idler Bolt Lock Nut 1/4"-20Bolt 1/4"-20 x 1-3/4HARDWARE SHOWN ACTUAL SIZEASSEMBLY STEP 2Fasten the Rail to the Motor Unit• Insert a 1/4"-20 x 1-3/4 bolt into the coverprotection bolt hole on the back end of the rail asshown. Tighten securely with a 1/4"-20 lock nut.Do NOT overtighten.• Remove the two bolts from the top of the motorunit.• Attach spreaders to the U bracket by snappingthem into place.• Place the U bracket, flat side down, on the motorunit and align the bracket holes with the screwholes. Fasten with the previously removed screws.• Align the rail assembly with the top of the motorunit. Slide the rail end onto the U-bracket, all theway to the stops that protrude on the top andsides of the bracket.