I have a little experiece w/GDOs. Basically, GDOs have settings for how far the door travels in each direction and how hard it closes. If no one has fooled around with the settings then your door system may be out of adjustment. Check the track and make sure the door does not bind up going up or down. Do this by disconnecting the trolley (pull the string/chain to release it). If the door binds the track or door hardware may be worn. Make sure the track is not loose, etc. If it is binding then the sesitivity setting is detecting the extra effort to shut the door and is causing it to back-up. This setting is important due to children playing in the vicinity and, if the door closes on one, it should feel sense the blockege and retract. Make sure your door hardware (wheels, chain/screw, etc are lubed. I use spray (WD-40) on the wheels and lithium grease on the chain/screw. Also, If the torsion sprigs are weakening or have slipped a turn or two then there will be a higher resistance for the opener to overcome. The dpringe act as counterbalances that help the opener by taking much of the weight off of it. If you cannot easily lift the door with the trolley disengaged, and the door won't stay open without your help, then suspect the springs. Usually one side or the other has slipped. If so, you'll notice the number of turns (look at the painted stripe on the spring) of one spring will be less than the other. Hope this helps. If there settings are out of adjustment then post that and we'll see what can be done then.