X20 bad USB port

[claudeo]

Friend's X20. All works well but she once plugged in her mouse upside down and gave it an extra push. Now the USB port no longer works. The mouse still works in the other port. Things seem to work in the damaged port if they have their own power, so it looks like the +V supply might be shot. Either that or something is cracked in the connector itself, but it does not look that way. Before I waste any time on this, I'm asking this question: Is there some kind of fusible or sacrificial component in the circuitry for the USB ports to protect the driver chip and/or the MB? If so, is it replaceable without replacing the MB altogether?