IF it must be stock and you cannot buy a replacement your only choice is to rebuild.
IF it runs now then you may get away with just truing up the commutator & undercutting the mica. Wash windings with soap n water and paint brush chase with isopropyl and oven dry. Find a motor shop that will dip n bake new varnish. Reassemble and test.
IF a rewind is needed that is going to cost $$$$. Large motor shops more than likely will not touch it.
Automotive electrical rebuilder may be willing to do it.
Dan Bentler
