I just replaced my older chain drive garage door opener with a new belt drive. It works fine except for one thing.It fails the safety reversal test. It passes the the protector system test so I know the sensors are working. If I adjust the the down force the trolley moves to far and the opener rail starts to arch upward.
I suspect it from the spring/trolley nut. I did something wrong and it is too loose;should be about 1 1/4 in long but is 1 1/2 in long. I am trying to compress the thing but have no luck. The nut ring moves around as does the trolley shaft. It's like trying to put toothpaste back in a tube.
Any advice is appreciated.