Dennis wrote:
You mean that when the door is closing, it went further than it should
and hit the floor too hard and thus causing it to reopen?

Yes. The 'down limit switch' is telling the opener that
the door had not closed. So the opener has only one choice;
that is to treat the garage floor as an obstruction,
triggering the re-opening.
Your 'down limit switch' is adjusted on the 'edge' of
working properly.
Sometimes it forces the door on to the garage floor,
sometimes it sees the floor as an obstruction and re-opens.

Does this sound familiar?

Buildings move as they settle. Doors jam. Windows stick.
Same thing here. You can't jack the settled side of the
door jam back up, so you readjust the opener.

How about the jerking when it opens?
Both of these symptoms are consistent with the same cause.
(I don't know if I mentioned that.)

Watch the opener carefully as it closes the door.
You will see it bend a little as it stores the energy it took
to force the door on to the garage floor. When you open the
door, some of that energy returns in the form of a rebound.

That is the jerk you see.

Here is an Experiment:
http://www.genieremotesonline.com/im...Switch_001.jpg
Mark the position of the 'down limit switch' (with a magic
marker) on the track. (Then photograph it with your
digital camera.)
Loosen the 'down limit switch' and slide it back, toward the
opener motor a couple inches. Tighten it in this new position.
You should see daylight under the garage door after it closes,
but the jerk will disappear. You will find a place on the
arm of the opener for the 'down limit switch' that will
allow the door to close securely yet not rebound as it does
now. Just move the switch to that position and tighten it
in place.

You have nothing to lose here. If the experiment doesn't work
in this manner, you can slide the limit switch back to it's
previous position and you are back where you were.



--Winston