Novak Rotor Replacement Know How

[Benh]

I am changing the rotor in my Novak motor. The new rotor is supplied with 4 shims. The existing motor had one shim on it.

Putting 1 shim on the new rotor resulted in horizontal play. Something I have noticed before on "out-of-the-packet-motors". But how much should you have/ not have. There is nothing in the Novak paperwork about this and wonder what your experiences are. I have placed 3 shims on the rotor and now there is no play at all. But should there be?