I guess this is a fixture(?). I noticed gap adjustment plates on a SCMI bandsaw and thought "Now here's a practical use for those AARP cards they keep sending me . They're no good for shims becasue the lettering is raised.
Original gap is about 1" x 2" . Surprisingly, it does seem to help quite a bit. Of course, a larger DC would probably solve the issue more elegantly.
Brush backed off for clarity.