Hi,
You need to clean the commutator, its full of gunk and if you meter it, no doubt it will be shorting across the commutator contacts.
My engineer friend and I have rebuilt 8 vac motors that i kept but were useless (im a hoarder) using a bucket of water, soap, brush and a new set of carbon brushes. Done 2 pumps this way and 3 kirby motors.
Carbon isnt your friend inside a motor.
Graeme
Access Cleaning Solutions
PS MAke sure its dry before using it again