Hi all - any help is greatly appreciated.

My garage door opener (an older Sears/Craftsman 1990) has started
throwing off the chain. The sproket is in good shape (was replaced a
few years ago) but there seems to be a collar or bushing missing (or
broken) from the shaft that goes down into the housing. When garage
door begins to lift, the sprocket is pulled forward, tips slightly, and
throws the chain off. Do I need to replace the entire assembly? Do I
need a technician?

Thanks.
Bruce

wrote:
Hi all - any help is greatly appreciated.

My garage door opener (an older Sears/Craftsman 1990) has started
throwing off the chain. The sproket is in good shape (was replaced a
few years ago) but there seems to be a collar or bushing missing (or
broken) from the shaft that goes down into the housing. When garage
door begins to lift, the sprocket is pulled forward, tips slightly, and
throws the chain off. Do I need to replace the entire assembly? Do I
need a technician?

Thanks.
Bruce

You need the Part #41C4220 Drive & sprocket set which has the
sprockets, shaft, & bushing w/ mounting plate. Remove the (3) screws
(believe they are metric heads) holding the plate to the motor head &
the whole assembly pulls out thru the top.

Make sure you don't have the chain too tight when you put it back on.
With the door disconnected from the opener the chain should sag approx
1/2" in the center. Also make sure the door works easily by hand in
both directions.

Doordoc
www.DoorsAndOpeners.com

On 6 Jun 2005 08:06:45 -0700, wrote:

Hi all - any help is greatly appreciated.

My garage door opener (an older Sears/Craftsman 1990) has started
throwing off the chain. The sproket is in good shape (was replaced a
few years ago) but there seems to be a collar or bushing missing (or
broken) from the shaft that goes down into the housing. When garage
door begins to lift, the sprocket is pulled forward, tips slightly, and
throws the chain off. Do I need to replace the entire assembly? Do I
need a technician?

Thanks.
Bruce

Check to be sure the sprocket is properly oriented. On my Sears opener,
the spocket has a collar that can point either up or down depending on the
particular opener and where the sprocket needs to be positioned.

Thank you! I will see if I can find that part here in Ottawa, Ontario.
Anyone know of a place?

Thanks again - this worked perfectly and was fairly simple.

The only thing that got me stuck for a few minutes is that on the
bottom of the shaft, there is a plastic gear held in place by a plastic
retainer clip - once i removed this the whole unit came smoothly out
the top and I was able to install the new part.