Sorry, have no idea where to get parts. But I do have a question. :-)
I haven't run my generator yet (one of the lucky, lucky few whose power didn't go out this time), so I don't know whether to believe the manual or not. It says I'll get 9.1 hours out of an 8 gallon tank at full load (6kW). I'm guessing it'll be even longer at less than full load. That seems like a really long time for 8 gallons of gas. How big is your tank, and do you know how much power you're putting out?
(I don't know where to get the special connectors, but I bought a 10 guage 100 ft extension cord and a portable GFCI at a place called "MegaTools". Looks like a contractor supply kind of place. I'll bet Home Depot or Lowes will have that kind of stuff.)