Don't forget that where the poles of the magnets are in relation to the brushes affects the power output and speed of the motor. So you may have to move them around the case to get optimum power.
Based on where the poles are in the original rubber magnet, the "S" and "N" poles go directly at the top and bottom of the can. I can't remember which one goes where, at the moment, but the point is that top and bottom, as you look into the back of the can, is where they go, and I am replicating that behavior with my magnets. By taking a simple ceramic magnet and holding it near the ring magnet, the ring will spin and stick to the ceramic magnet exactly on one of its poles. So then you just mark that spot on the ring magnet and put it in the can so the mark is dead top (or dead bottom). If you get it wrong, the motor will spin backwards.
