I have 2 USB axis cards. On one, when I plug in the USB cable the led stays on all the time, on the other the led never comes on. I'm not sure what is supposed to trigger the led or what it is supposed to indicate. However, on the one where the led doesn't come on, when I connect 10k pots to J3 or J4 the numbers go from 16383 to -16383 long before the axis reaches the end of its travel. On J5, J6 & J7 they work just fine. I swapped them around just to make sure it wasn't just a bad pot. Is the problem with the IC or could it be some other component?