Sliding door roller
A professional from Sacramento, CA says:
August 6, 2016
The patio door has only one long screw on each side (appx 2"), at the bottom, to adjust the roller and to take the bottom section of the slider door off. The housing has become too worn where the wheel is attached causing poor adjusting. It will not raise up enough.
Dave from SWISCO responded:
August 10, 2016
I'm afraid I can't find a roller quite like this. Could there be more to it? Check the door to see if there's an outer housing still installed.