Herr, make sure that you adjust the air gap set screws on the
2-speed clutch shoes correctly (the screws that are in the center
of the shoes). Here is a pdf. for the Ofna (shoe type) 2-speed
clutch set-up. The center shaft is different on the 2-speed in the
pdf., but the shoe adjustment description is the same.
http://www.ofna.com/pdf/8-Shoe-2speed.pdf