Does anyone know why my Stanley garage door opener will only "learn" shut properly 2 or 3 times in a row. Then it tries to drive the garage door thru the floor soo hard it breaks the plastic gears inside the opener. I've set all the tensions & it will work 7 or 8 times in a row, then all of a sudden closes soo hard it almost breaks the pole in 1/2 and snaps the gears. I have 2 of the same doors, replaced the gears 3 times now. time to buy 2 new openers or does anyone have any suggestions? Thanx...