Garage door will not stop and hits the opener itself

Replaced the gear in my opener. There is power chain tension is correct. The opener does not stop and wants to hit the opener itself instead of stopping. If I take the chain off and position the bracket at the end of the rail, then the door doesn't want to stop on the way down. Have tried adjusting the up and down. No luck. Do I need to reset something?
Asked Jun 26, 2016

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