I don't have a manual, heck, never seen a manual for one. Here's link to some scans from an old magazine that has a brief description and shows it dissasembled
Old Magazine Scans
And I think one of those screws (maybe the longer one?) is actually a choak type velocity adjuster. I know on mine I was able to adjust the velocity by sticking an allen wrench in to a hole in the right linkage cover and tightening or loosening a small allen screw.