OK, a quick test, if you can't hear the air-over working can you feel air pulsing out of the vent on the side of it? it shold be a few pulses per second if it's shuttling the air piston (A09 in the diagram).
I was planning to buy one of these when I get the Circular Tuit, be good to know they work...
Dave H. (te other one)
just checked this afternoon and yes air is coming out of the little hole on the side.
oh and a little bit of oil that I put in as instructed.