Many times in motor failures, the cause of fail is not electrical but rather
mechanical. Armature bushings wear out allowing insufficient clearance
to the field assembly.
Electrical failures are not that easily identified with a VOM. If you have
an electrical open, it will be quite obvious. On the other hand, if there
is a couple of windings shorted together, it is sometimes impossible to
identify with a typical Ohm meter. An impedance analyzer would be most
useful in this situation and probably the only instrument - in most cases
where failure is caused by a shorted turn - able to detect where the fault
lies.