Hello, thank you for requesting me.
There are only 2 possibilities here:
1. Bad inverter (it is not servcieable).
2. Bad stator.
Open the maintenance access door.
On the inverter, remove the 6 pin connector that has 2 gray wires and 3 red wires.
Holding the plug with the locking tab up, and the pins facing you, the wires are identified as, from left to right, starting with the top row: Gray 4, Red 1, Red 2.
Bottom row : Gray 5, empty, Red 3
Being VERY careful, start the genset, and manually move the throttle open until the engine reaches a speed of about 3500 rpm.
With your meter set to VAC, test from Red 1 to Red 2, then from Red 2 to Red 3. Bot shoul read 250 - 260 volts.
Then test from Gray 4 to Gray 5. It should read 8 - 16 VAC.
If any of those readings are bad, the stator is bad.
If those readings are good, the inverter is bad.