Never had a problem with Graves Index gears. First, make sure they’re clean. Use a stiff brush to clean the notches. Second, make sure the tension is correct on the index pawl. It may not be adjusted correctly. There’s a set screw on top of the pawl. Using the 1/16″ Allen wrench supplied with the machine, tighten it a little at a time until the index wheel is hard to move when the pawl is in a notch.