I was thinking you had more font-back play than side to side play. If you have side to side play, that is not good at all. Take the bell off teh crank again and look at the bearings. Are the in good shape? If the shields are gone and the little balls have fallen out, the bearings are of course shot.

Also, most clutchbells are designed to have two bearings. One in front of the bell and one in the inside of the bell to assure stability and no side-to-side play at all. If you are missing one of the beaings, go ahead and get another. You can ask Andy to send you another, or you can probably find the exact same size bearing in your local RC store. All you have to do is know what size the bearing is. Traxxas, HPI, Mugen, and several otehrs have metric bearings. If your RC uses inches, AE has bearings in inches.