I worked on a DG-300 that was always a haste to rig. Finally, I removed all lubrication from all 4 lift pins and then painted them black with a magic- marker. Forced the wings onto the lift pins, then slid them out..............magic-marker was removed from the aft side of the aft lift pins and from the forward side of the forward lift pins! Then I jumped on the indicated interference areas with emery cloth cut into 1" strips..............scrubbed them like shining shoes. Took over an hour, but that damned thing finally rigged like it should.
Cheers,
JJ