I jumped the gun here. The spindle is now reinstalled. I tightened the set screw on the back gear and I can easily engage and disengage the pin, allowing the back gear to free-wheel from the pulley or not. But as soon as I tighten the set screw for the pulley, everything's back to where it was--pulling the pin out is tough but doable, and I can't get the back gear to free wheel. Loosen the set screw on the pulley, and everything's fine. Obviously, the pulley set screw has to be snug. Any thoughts? Might the problem be with the pulley--perhaps it's out of round for some reason?