if you see it spin by looking into the intake side it's working. The heat of the exhaust is what makes it spin faster when the engine is under a load. The heaver the load, the more heat, the faster the spin. DO NOT stick your finger in there. We had a guy in tech school try to stop a turbo at idle on a little Deutz diesel. It took the finer off up to the first knuckle. Myself and 2 other guys had the honer of tearing down the engine looking for the finger since it happened in my class. We were hopping it was in there. It cut that thing off and sucked it through and never miss fired.
Also I herd that bypassing the timer / voltage reducer can destroy the glow plugs. So be careful with the button.