Craftsman 139.53959SRT Owner's Manual page 8

ASSEMBLY STEP 1
Assemble the Rail & Install the Trolley
To avoid installation difficulties, do not run the
garage door opener until instructed to do so.
The front rail has a cut out 'Window" at the door end
(see illustration). The hole above this window is
larger on the top of the rail than on the bottom. A
smaller hole 3-1/2" away is close to the rail edge.
Rotate the back rail so # has a similar hole close to
the opposite edge, about 4-3/4" from the far end. A
3-piece rail uses two back rails.
1. Remove the straight door arm and clevis pin
packaged inside the front rail and set aside for
Installation Step 12.
2. Align the rail sections on a flat surface exactly as
shown and slide the tapered ends into the larger
ones. Tabs along the side will lock into place.
3. Place the motor unit on packing material to protect
the cover, and rest the back end of the rail on top.
For convenience, put a support under the front end
of the rail.
4. As a temporary trolley stop, clamp a locking pliers
onto the rail, 8" from the center of the idler pulley
hole, as shown.
5. Check to be sure there are 4 black plastic wear
pads inside the inner trolley. If they became loose
during shipping, check all packing material. Snap
them back into position as shown.
6. Connect the inner and outer trolleys as shown.
7. Slide the trolley assembly along the rail from the
back end to the locked pliers.
Back Rails
(TO MOTOR UNIT)
Tabs
Outer Trolley
Inner Trolley
Front Rail
(TO DOOR) _Wear Pads