Thanks for the manual, I will download and check it out. I have one photo handy of the gov, which I was going to post anyway asking if it is always so tricky to setup... I have used the 'attachment manager' to upload the photo, is that the best way? Following a youtube video I found, it said basically:
1. Loosen the arm clamp 2. Push the butterfly wide open 3. Turn gov shaft fully clockwise 4. Tighten clamp.
That got me close, but not quite right, I fiddled from there with very tiny rotation of the shaft from the initial set position, as I said still not perfect but close.
Good call on the air cleaner, I'll try that and report back, it certainly has that choking kind of sound under load like a blocked vacuum cleaner