dean wrote:
Could you tell me what the limit controls look like? I have had the
cover off and stared at the thing for a while, but it was confusing, as
when its opening its moving so fast I cant see whats happening very
well.

Look at the limit adjustments, and see where they connect internally to
the overhead unit.

Or snap some clear photos (emphasis on "clear") of the insides and post
them at a place like Glowfoto.com or Flickr.com so everybody can look
at them.