Offered for sale is a Chamberlain Garage Door Operator Gear and Shaft Assembly, Liftmaster Part Number 41C4220, New.  This assembly comes with the gear and shaft assembly, a motor worm drive gear, a motor shaft bearing kit, and a tube of gear lubricant.

    Symptoms of shaft failure are: the chain or chain and cable assembly begins to droop below the rail, and tightening the chain adjustment doesn't help; the small toothed drive sprocket on top has snapped off.  Symptoms of gear failure are: the motor will run, but the chain or chain and cable doesn't move, a loud grinding noise comes from the operator.  Failure of the rear bearing usually results in excessive play in the motor shaft, causing the white drive gear to strip.  This all presupposes that the overhead door is in proper working order.

    This kit will work on any Chamberlain operator ( Sears Craftsman, Monark, Master Mechanis, Wayne-Dalton, Raynor, Liftmaster, Chamberlain ) that uses this same gear and shaft assembly.  You may need to remove your operators housing to see if this is the right part. 

    If you have any questions please use the "Ask Seller A Question" forum.  Please read my terms before you purchase.  Parcel Post domestic shipping can take from one to three weeks.  Seller is not responsible for the length of time it takes the USPS to deliver.