Hi bigted,
The mower had one of those rubbber rings underneath around the disk, I took it off as I don't use a catcher. I think it is a vortex.
Yes it runs at 70% irrespective of throttle position.
Here's a pic.
randell [Linked Image]
It has TUR......... on left side, maybe Turbo....

randell

........................Keep your blades sharp......................