The inside of the notches on the cutting blade are quite rough and I found this jammed the thumbscrew. To get the mechanism to work smoothly, I had to use a fine file to clean up the inside of the notches.. Finished up with sandpaper wrapped around a small file or paddle to polish the inside of the notches (up to 400 grit). . I too had to tap the adjuster screw to ensure it was parallel to the cutter. After these adjustments it works perfectly.