[john70t]

The screw is in the little hole on the flat area between the rubber sensor plate boot and the fuel plunger part(with the ring of hoses coming out of it). I sprayed a little WD-40 very carefully in there but it is not good for rubber.
Use very light pressure and just the fingertips and rotate it to fit it in. That is a delicate area and the hole may have a cap or be filled with dirt (hope not-CIS does not like dirt or vacuum leaks).
Right is richen, keep engine off when adjusting, don't push when turning, and turn no more than an 1/16 th at a time, start, rev up and recheck, take the tool out inbetween or you'll bend something and buy a new distributor.
The mixture is pretty sensitive so go easy, good luck

I think Bosche owns the patents on CIS and the D and L jet/motronic (on all the modern cars). I think Chevy used a version of the CIS on some years of the corvette to get around royalties.