You want some play. You want the bell to have some play on the shaft, as in you can slide it along the shaft approx 2 mm. You also want a little bit of play in the gear mesh, but just ever so slight. I simply slip a piece of paper (about 100 thousands of an inch (.100)) between the bell and spur gear when I am tightening my motor. That usually works pretty good for setting gear mesh.
If you truly have NO play on the clutch bell, I would check your shims. It is possible you can simply remove a shim and be set. If you are using no shims, double check and make sure the bearings are not bound a little in the bell. Push on the bell hard to make sure the bearings are seated all the way.
Hope this helps.