I don't think there should be that much play in the rotary vane, but don't know for sure. It's only spinning one direction, the the gears might have some play in there.
Your vane also looks a little scored up and that might be leaking air though. Maybe take the cover off and check it as well as the timing of the vane.
Also clean our your rave valves as that also might be causing issues with the higher end power