Anytime the door reverses to the open position and the main light flashes 10 times it is a sensor problem. Sometimes the sensors are aligned close enough to turn the receiver light on but not quite enough to satisfy the 'brain'. Tweak them just a little and try again. Also make sure the sensors are not loose and are moving as the door closes.

thanks, don.
Placed a level, horizontal and vertically on the sensors. Problem fixed!

i have a 1/2hp c/man GDO and i think i am having range problems. I will reset the system and then reprogram my 2 remotes and keypad into the GDO. They all will work fine in about a 2ft radius of the antenna sticking out the GDO, anything past that and they will not work at all. Have tried changing the batteries, thinking that could be the problem, but have the same issues. any ideas??

I had the same problem with my Genie GDO. It was a bad receiver board. Fortunately it was still under warranty.