Hi and welcome to FixYa, I am Kelly.
The Service manual is here:
http://www.generatoremporium.com/pdf/IG6000-service.pdf
Since you stated that you had no 240V output... Perform the alternator winding tests para 2 - 6 on page 12 of the above link. Hopefully this test passes! Do this first.
This is straight out of the service manual: (pdf page 16)
b. The engine speed does not increase when smart throttle is on and load is increased.
Check the AC output
?abnormal
Perform the generator troubleshooting flowing the instruction of "No or Low AC output
There are more troubleshooting steps after the above. The usual suspects are the stepping motor and the smart throttle switch.
The
stepping motor resistance checks are on page 27
Also make sure to perform the diode checks on 30 and 31.... (Voltage regulation and charging)
What they do not tell you is that an inverter generator uses a capacitor as part of the voltage regulation and a bad capacitor or.... hot terminals on the capacitor wires where it routes to the stator can stop all voltage output. Often the signs of a failed capacitor are... what appears to be candle wax directly under it or... the capacitor(s) are swollen in the terminal area.
You have everything you need to determine what the problem is by using the manual. If you have more questions at a later time ask away. I will gladly help you.
Thanks for choosing FixYa,
Kelly