On Thu, 2 Jul 2009 10:13:52 -0700 (PDT), "
wrote:

Hi, I have a 10 year old garage door opener. When the garage door
opens, sometimes it jerks the door at the start, but the door opens
fine.
There are also few times when we close the door, the door will bounce
off the floor and reopens by itself.

Does it sound like a bad tension in the spring, or something else?

Thanks

The cause in my case was that the rubber on the bottom of the door was
sticking to a relatively new concrete stain which was applied to the
floor.
I applied a strip of duct tape to the floor in the area where the
rubber was sticking, and the problem disappeared. I was told to apply
some paste wax to the rubber, but I never got around to it.
hth