The resistance isn't the measurement you want for this. While spinning the hub by hand look at the Voltage AC. This will tell you the interaction between the exciter ring and the sensor. I believe it's supposed to be above 250 mV, mine were 100-110 before I cleaned them, over 400 after.
You can get a seperate sensor without the hub, I broke one pulling it out and had to get a new one, about $100 US.
Hope this helps!