I understand that heavy tool pressure will slow the wheel, but my wheel has recently slowed from very light pressure. Is there a way to tighten the motor/wheel connection?
There is no "tightening". The motor floats, and is supposed to.
The problem is that the motor shaft and the drive tire are losing friction with each other. This happens when one or both gets dust or some other foreign matter on them. Remove the leather honing wheel. Turn the machine on and hold a piece of coarse (80 - 120 grit -- whatever you have) sandpaper against the drive tire as it is running. Thoroughly clean the surface of the drive tire and do the same to the motor shaft. Apply pressure to the grindstone to test. You should be able to apply a lot of pressure to the grindstone with only a moderate decrease in speed.
Thanks Jeff - it works fine now.