Jim, from years of seeing the effects of hardened WD40 on clock works,
I'd advise against using it on electric motors, or at least, after the
motor is freed up, wash it with mineral spirits or gasoline to remove
the WD40 residue.  If you leave the WD40 its solvent will evaporate,
leaving the other substances to harden into a difficult-to-remove
varnish.

Bob Loesch, former clock repairman