[Elecraft] KIO3B Main Board Repair

[K4PI]

I have ended up with 2 bad KI03B boards E850645.  Both bad in the USB 
circuit.  I did some basic checks resistance wise they recommended but 
found no problems.  Elecraft said chances of repair was slim and would 
not be economical to try.  I think all the other functions are okay ie 
think they are still working okay if you come in via the serial port.  
Seems a shame to toss them into the dumpster  but unless someone has had 
some experience of repairing them that may be the route.  Anyone ever 
attempted at repair of the USB circuit on these?  73 Mike K4PI