If you pull the 3 wires from the AIU switch screw terminals, what happens if you momentarily touch the "IN" wire to the "1" wire, and separately when you momentarily touch the "IN" wire to the "2" wire? If you get the same sluggish or dull behavior, then it's not the AIU. When you press the AIU straight or turn-out switch button, all the AIU does is momentarily short (using relays) the "IN" wire to either "1" or "2" for exactly 1/2 second.