My sliding glass door is hitting the center frame of the stationary panel, causing it to stop about 1/2 inch short of closing completely. The two frames are hitting and the door will not close further without major manuevering. It rolls fine otherwise. Is there a way to fix this?

May have to lift the roller back on the track.
You may have to loosenen the phillips in the jamb, next to the roller to get slack, then tighten back up to lift into place.

I agree with Stramando. It appears that back roller is on inside of roller guide.

Chuck