I'm not following what your describing, got a picture? Near the front of the glass are the two clamping points that capture the front guide... In the rear there is a C shaped channel & an interlocking C shaped guide these each have a ramped wedge to more accurately locate the glass at the top of it's travel.. There are two felt covered guides as shown in the post above & there is a rubber covered piece but that limits the upward travel of the glass & has nothing to do with in & out position, it doesn't touch the glass, it hits a plastic stop that protrudes from the glass..... I suspect your looking for the travel limiter but you have it's purpose confused...