After replacing a worn/stripped main drive gear and worm gear, I can't seam to do anything to adjust the opener so the door will close. No matter what I do, it just goes down about a foot and then reverses and goes back up about 1-1/2 feet... then eventually stops at the upper limit. It never makes it to the lower limit switch, so downward travel adjustment isn't a factor. The downward pressure adjustment should make it continue down, but it doesn't seem to have any affect at all, even turned all the way up (clockwise). Any suggestions

By the way, the light does NOT blink, there is nothing blocking the safety sensors near the bottom of the door and the door operates freely - is well balanced. The same thing happens even if I disengage the door from the sled on the track... as in, no weight or drag at all.

This appears to be the answer to my question: See that you correctly replaced the plastic cup on the end of the motor shaft. You had to remove it to replace the worm gear on the motor shaft. It runs the rpm sensor and the unit will not work without it. That part got covered by rags on my workbench when I was cleaning up all the old grease and gear fragments/dust; so I had forgotten about it during re-assembly.