Craftsman 139.53910 - Manual (Page 9)

assembly step 2
Fasten the Rail to the Motor Unit
• Insert a 1/4’'-20x 1-3/4 bolt into the cover protection
bolt hole on the back end of the rail as shown.
Tighten securely with a 1/4’'-20 lock nut. Do NOT
overtighten.
• Remove the two bolts from the top of the motor
unit.
• Place the “U” bracket, flat side down onto the
motor unit and align the bracket hole with the bolt
holes. Fasten with the previously removed bolts.
• Align the rail assembly with the top of the motor
unit. Slide the rail end onto the “U" bracket, all the
way to the stops that protrude on the top and sides
of the bracket.
• Attach spreader to the motor unit with two screws.
CAUTION
To avoid SERIOUS damage to garage door opener,
use ONLY those bolts/fasteners mounted in the top of
the opener.
ASSEMBLY STEP 3
Install the Idler Pulley
• Lay the chain/cable beside the rail, as shown.
Grasp the end of the cable and pass
approximately 12" {30 cm) of cable through the
window. Allow it to hang until Assembly Step 5.
• Remove the tape from the idler pulley. The inside
center should be pre-greased. If dry, regrease to
ensure proper operation.
• Place the idler pulley into the window as shown.
• Insert the idler bolt from the top through the rail
and pulley. Tighten with a 3/8" lock washer and nut
underneath the rail until the lock washer is
compressed.
• Rotate the pulley to be sure it spins freely.
• Insert a 1/4"-20x1-3/4 bolt into the trolley stop hole
in the front of the rail as shown. Tighten securely
with a 1/4"-20 lock nut.