Hi,

I don't have a D3.5, yet, but for most motors:

- assemble w/o shims;

- spin by hand and press arm each direction, one direction after each spin, and get an idea of how much shimming is needed (or measure with calipers) on each end;

- re-assemble and repeat until it has little to no sideways movement through the bearings.

Even non-slotted (less notchiness, do I understand that terminology correctly?) motors will resolve and center the rotor as it spins.

If it seems properly held in the magnetic gap, but feels a little marbly when you rotate it, try one less very thin shim or replace a thicker one with a thinner one until the marbly grumbly feel goes away.

If that "bumpiness" doesn't go away after proper shimming, you might need to replace a bearing.

Gene