If you dont get all those seat o-rings in perfect you end up with bleed by (replace as unit). Have you changed the master cylinder as well? I always change them both as a set. The added pressure from one new brake component will cause the other, unreplaced, to leak, possibly internally.

As for the spacer, is this the aluminum u-shaped spacer? You can remove the top of the motor and hope... or remove the whole motor and remove the lower bell housing (w/o ser# hopefully no encoder). Advice for the future (had this happen to me, LOL....now), fold and stuff a towel under the brush holders when working on the brake assy. or changing brushes...try finding a brush mount screw in the motor of a Raymond swing reach...added hours n hours.