Craftsman 1/2 HP GARAGE DOOR OPENER 139.53978SRT - Manual (Page 10)

Assembly Step 4
Install the Chain/Cable
and Attach the Sprocket Cover
1. Pull the cable around the idler pulley and toward
the trolley.
2. Connect the cable loop to the retaining slot on
the trolley, as shown:
• From below, push pins of master link bar up
through cable loop and trolley slot.
• Push master link cap over pins and past pin
notches.
• Slide clip-on spring over cap and onto pin
notches until both pins are securely locked in
place.
3. With the trolley against the pliers, dispense the
remainder of the cable/chain along the rail toward
the powerhead and around the sprocket. The
sprocket teeth must engage the chain.
4. Check to make sure the chain is not twisted, then
connect it to the threaded shaft with the
remaining master link.
5. Thread the inner nut and lock washer onto the
the trolley shaft.
6. Insert the trolley threaded shaft through the hole
in the trolley.
Be sure the chain is not twisted.
7. Loosely thread the outer nut onto the trolley
shaft.
8. Remove the locking pliers.
9. Align the tabs on the sprocket cover with the slots
in the mounting plate. Squeeze cover and insert
tabs in slots.
Master Link
Clip-On Spring
Serious injury can result if fingers become
entangled in moving opener sprocket. Attach
sprocket cover securely. Never operate opener
while your hand is near the opener sprocket.
Dispensing Carton
Master
Link Gap
Idler
Pulley
Cable
. Master
Link Bar
Trolley 1 I
Pin
Threaded ' ' Notch
Shaft I I /
XjnC—
^ UnkBar
Round
Hole
Sprocket -
Cover
Opener
Sprocket
Back
Tab Slot
Mounting
Plate
10