i have a craftsman garage door opener, approximately 17 years old.
i've noticed the chain is sagging and the door only opens up 1/2 way
due to it getting stuck or caught on something - can anyone help with
this problem? we've had the springs replaced and that doesn't seem to
be the problem, just the sagging chain.
There should be an adjuster which lets you take the wear slack out of
the chain/cable. On my Crapsman openers it's built into the traveling
carriage to which the door arm attaches.
Look for it, and do what it takes to tighten up the chain a bit.
On Jul 9, 1:19 pm, email@example.com wrote:
With the door disconnected from the opener (no load) there should be
approx 1/2" of sag in the chain.
As usual, the first thing to try is to disconnect the door & open the
door by hand to see if it opens easily & freely. If it doesn't look
for something catching the door by the track (like broom handle, etc
or the door lock partially engaged. If it does move freely run the
opener w/ the door still disconnected to see if it stops without any
Does it open exactly half way or is it stopping where the rail is
spliced together (usually 1/3 & 2/3). If it's stopping at the splice
bend the four taps up slightly on the inner carriage (part that door
arm connects to). These tend to catch on the splice, but don't bend
them up to much or the outer carriage part won't go past them to re-
connect the door.
Inspect the the shaft & the motor head sprocket on top of the unit
that the chain goes around. The sprocket is welded to the shaft & they
have been known to separate from the shaft & they bend upward until
they break completely. Also make sure that the shaft is pointing
straight up & down. If it appears that it is leaning toward the door
the bearing that the shaft is going through is probably worn out. This
is another known problem & over-tightening the chain or a heavy door
will make the problem occur even sooner then normal. This part is an
assembly that includes the shaft, chain sprocket, bearing plate, &
plastic drive gear, but does not include the limit gear sprocket at
the bottom of the shaft. After you remove the limit gear & the 3
screws holding the bearing to the motor head the whole assembly lifts
out from the top. If you remove the chain do not move it until you put
it back on the sprocket & put it back as close to the spot as
possible. If you move it to much or run the opener without the chain,
you will have a heck of a time getting the limits reset. Also please
note that the 3 screws holding the bearing plate are a metric size.
Yes there is a threaded rod on the chain to tighten it, but only
tighten the chain in this manner after you have verified that there
isn't something else causing the chain to sag.
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