When you were removing or replacing the shaft, you must've had a gap between the temp shaft and real shaft, allowing the wheel to move. The only way I can think of correcting, is to take it apart again & re-do. To avoid a wheel moving; when the temp shaft (nail) is pushing the real shaft out, make sure they stay in contact so none of the wheels get loose. To fix yours, you will actually need to allow a gap so that one wheel is freed up. It'll be tricky but you can do it. Good luck!