Use these thrust washers between the e-clip and rear bearing, or between the can and front bearing.  They are sized to contact only the bearing inner race and avoid any friction caused by contact with the outer bearing race or other stationary parts.  Installed at the rear bearing they prevent the e-clip from contacting stationary parts.  That assures lowest possible friction.  Used at the front bearing they provide additional running clearance between the can face and the windings.  Just what you need if your windings turned out a little too fat.