The Graves index wheels aren’t very consistent. On each wheel there are a few notches that don’t engage positively. I eyeball them and make sure I seat into the center-ish of the notch, which is essentially a cheat adjustment that I can’t be sure I’m replicating 100% when I return to that notch. Can I use index wheels from another machine? Is it possible to fix these ones? At my skill level the problem is minor, but I can imagine cutting a complicated design where plus-or-minus-.25-degrees could really throw things off.
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.