My Evcon furnace will ignite but the blower motor just hums and the blades won't turn.When the motor is off the fan turns freely.Is the motor shot?

It could be the motor or the capacitor. I would go with cap first. When the motor hums, see if you can get it to rotate by pushing the cage with a paint stirrer or other small piece of wood-Do not put your hand inside. If the motor starts, it is most likely a capacitor. Replace it with one having the same ratings.