Does the chain have stops to operate limit switches at end of travel? UP and DOWN?

I do not see any.

IIRC, my Sears chain drive opener had metal clips/stops that attached to the chain and set the up/down limits. There was a lever on the top of the housing and as the chain moved in one direction it hit that lever and that made the door stop.

Bruce

There are no clips.

Geoff D.

What have you actually done to attempt to correct the problem?

Do you have the Manual? Model Number. What would happen if you loosened the chain, "slipped" it 18", and re-tensioned it?

Stax. You are great. A friend stopped a little while by and we put our heads together. It is an electronic controller. He saw (what I didn't) that the controller could be removed from the unit allowing us to adjust the main spindle. We first were able to set the garage to the down position and recalibrated from there. Worked like a charm! Thanks again.