"yourname" wrote
It would have this mysterious symptom. close almost all the way down, then
stop reverse and open. Drove me nuts. turned out it was the stupid rope
getting in the way of the sensors. Happened again last week, after not
having it happen for more than a year. Rope wasn't in the way[tied a knot
in it] Looking looking, checking switches.......there was a tiny leaf,
suspended on a spider web on the door, dangling in front of the sensor.

Heh, reminds me of a little thing I encountered with my 16'x7' Wayne Dalton.
The door would open fine, but would not close with the vehicle remote or
wall switch, at exactly 7:15 in the morning.
Hmmm.....took me a little while to figure it out.
Turns out the rising sun in the east (my house faces north) would shine
right into the lens of the sensor.
A 2" piece of garden hose slipped over the sensor stopped that issue.
BTW: This would only happen at a certain time of the year when the sun was
at just the right angle.