I have two of these CH 1000 Door openers working in my garage.
The chain runs to an idler sprocket
attached to the wall above the door.
One of those push-pull rods attaches
one end to the door about a foot below the top & the other end of the rod attaches to a slider that the chain pulls back and forth. There are stops on the chain that hit the stops on the drive unit which reverses the direction of the chain next time it's actuated.
If you'll send me an email at [email protected]
I'll send you a picture or two of it.
Where in the world did you purchase the door drive assembly? I need one of the circuit cards that mount inside the drive unit, but I'd be glad to purchase the whole assembly just to get the card - - - unless it costs a zillion bucks.