Get out your 6' step ladder and put it so you can get up eye level with the back of your opener. You have two things to adjust here; the limiter switch and the tension knob. The limiter switch on many genie openers is a unit clamped to the travel bar near the door header. It should be positioned so that it tells the opener to quit pushing the door closed right when it hits the floor. The tension knob should be adjusted so that when it does touch the floor it doesn't do it with so much force that it deflects the traveler bar by 2", nor will it crush the skull of your two-year-old. In your case, I believe the tension is probably set okay, but the limiter switch needs to be adjusted.
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