The sprocket that moves the chain on my Craftsman 1/2 HP garage door opener stopped working in one direction. This caused the chain to be very slack on one side and extremely tight on the other. I managed to remove the chain, but the sprocket won't move at all now. I opened the box part of the unit and can see no obvious damage. Can anyone please advise? Thank you.
Can't see it from here, or your word-picture, but some obvious facts:
1) whatever shaft the sprocket is on is not free to turn. 2) some failure is causing that- like debris in gears, frozen motor or bearing, whatever.Either it's absolutely frozen, and cannot be budged in either direction (likely caused by frozen shaft bearing) or there is some angular play at the sprocket. The latter would indicate problems further away, in gear train or motor, or whatever else they put in there.
Really best you ask someone who can put an eyeball, and hand, on it.
J
Damage inside the gearbox is often not visable but is generally the one thing that cannot be fixed. Try rotating the motor manually and see if the output of the gearbox moves. Check the seam around the sealed gearbox for expelled lubricant (a sign that the body buldged open and spewed grease). Check for cracks or outward dents on the gearbox body. Try adjusting the up and down force knobs on the drive unit
Need a little more explanation of what you mean when you say the sproket doesn't move. Do you mean when the motor runs or when you try to turn it? You will not be able to turn the sproket by hand but you should be able to turn the motor by hand and that should also move the sproket.
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