Craftsman Garage Door Issue

I am having a problem I hope someone can help me with. I just replaced the plastic gears in my Craftsman 1/2 HP garage door opener, and now the motor wants to turn one way for about 2 seconds, stop, turn the other way for about 2 more seconds, then stop completely. This even occurs when the garage door is NOT attached to the garage opener.
Is there a reset button that I can't find on this unit? I've taken the load off the motor, checked all stop contacts (which are all open - not the problem). What might be wrong? I've called Sears, but to no avail. Responses can be either to newsgroup or email. Thanks in advance.
Regards,
Tim
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Krebs wrote:

yrs. old... but from experience with working on it the past 25 yrs. i would say that anytime a motor goes one way and then back the other way by itself is that its being jambed and setting off the motor inside to opener to twist and then the contacts on the reverse mode go into action... this is to stop the g/door opener to not hurt anyone or damage something... take a look inside (have the sheet metal case off when it does it to see whats jambing up and making it go the other way...if you had to replace the gears(they probably broke due to something jambing up and letting them break... i got a screw drive on mine... i would take the screw off and run it to see whats the problem... you might have a chain drive.. if so then take the chain off and see if it works correctly=by not reversing???? if so then you work from there back to the other sprocket.. and so on....
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Jim, The speed sensor cap/cup that mounts on the motor shaft is not seated all the way down, It is shaped so that the serated cup pases through a sensor receiver on the board to detect when the unit slows down or stops. It thinks you are stuck because it isn't getting a count. Frank Garage door Opener Problem Repair FAQ
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I did the same thing. 2 things need to be reset. First is normal travel range. You altered the 'timing' when you reassembled the gears. You should have 2 travel controls. Adjust them until you begin to get more travel in the direction you need. Keep adjusting until you get all the way. IF you don't get all the way, you will need to reset the actuator timing, write back. The second adj. is the load stops. You should now have less load because the freshly greased new gears work better, right? After the travel is right, adjust loads stops until they both just barely allow the door to go all up or all down.
Tim S.

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snipped-for-privacy@yahoo.com (Krebs) wrote in message

Did you put the revolution counter cup (small round black plastic w/ notches in the side) back on the end of the motor shaft & is the revolution conter board seated properly. The cup should be going through the middle of the board & the board produces a timing pulse thru the notches in the cup. This is the part that makes the door reverse when it hits something. When the timing of the pulse change from the motor slowing down it reverses. Therefore if the cup is not in place properly the opener thinks the door is hitting or catching on something.
Doordoc www.DoorsAndOpeners.com
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