I don't know how many people have had an experience with the AAV seizing up, but I thought I would share what I did.

After all tries at freeing it up failed I simply found a suitably sized coin (South African 20c works perfectly) and dropped it down the inlet tube of the AAV (this tube has a SLIGHT taper to it) so as to cover the "mouth" that the piston should otherwise close, and then seal it off with some automotive sealant. Doing this at least still offers you the usual idle adjustment, the only drawback being low idle when cold (usually about 250 rpm lower when cold than warm).