I installed a new circuit board in my Stanley Pro Series Garage Door Opener. All went well, except that I forgot to reengage the [trolley? Traveller? Whatever it's called] to the door after having pulled the red emergency cord, I before I taught the UP position.
So when I taught it "up," I think I went too far, since I didn't know when to stop (because the door isn't attached to it so it was just the chain moving).
When I try to reverse it, or teach it "down," the chain just lurches and stops, without reversing.
Clearly I need to get the part on the chain that hooks to the door, moved back towards the door, but right now it's hidden directly above the opener itself.
Any suggestions how to do this?
Thank you kindly.

another way to go would be to take the master link out of chain and move chain to a position where you can lock in trolley.the trolley might be jammed up from going to far.hope this helps please rate my answer thanks