The next step is to locate the uln2003 chip on your stepper driver. If your board does not have one, you can order one online for about 50 cents. If your board has a uln2003, you must desolder the chip from the board. This step can be a bit tricky, but is not that hard. First, try to remove as much solder as you can using your desoldering pump. Once you have removed the solder, use gentle, prying force with the tip of a screwdriver. Carefully touch the tip of your iron to each pin, still applying force with your screwdriver.