Yep the set screw that holds the swash plate to the motor shaft is missing. This could very well be your overall problem. Replace that and then run it. If the motor still fluctuates, your motor has gone bad or , more likely, you got oil into the motor. There was a"memo" a couple months back to stop oiling the Gen 6 and 7. People were putting too much and it was running down the shaft and into the motor. This happened to me.

Contacted Swash thru email, sent it back to be fixed. I think the whole thing took about 2 weeks, mostly due to customs. Great people and great customer service.