If it was tough to get the spur gear off then I would have to assume that its fine especially if it was the same resistance when putting it on. If you have it apart again, check out real closely the other gears with the magnifier as they cracks, if any, can be hard to see even to the trained eye. Also, I think there may be a large, flat, round gear that is being driven by the motors spur gear, its on a metal shaft of it own, make sure its not loose from that shaft and it meets the spur gear in its middle.
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