The shipped microphone is model no ACM1. The correct model is ACM1H. The model is on the original packing box the microphone came in.
The easiest way to submit a request is through Onkyo's website. I've read you can call or email, too.
(And FYI: your unit's serial # is on the original packing box, so you don't have to waste an hour trying to squint at it on the receiver in the dusty, shadowy back of your entertainment center.)
I submitted my request Sunday night and today received a confirmation from Onkyo
Thank You for contacting Onkyo USA Product Support.
Due to the holidays we are experiencing a heavy volume of inquiries. We apologize for the delay in responding. Thank you for your patience.
We will be sending you a replacement setup mic within two weeks.
Thank you, XXXX
I don't personally know how many units this affects in Onkyo's line. Audyssey is encouraging people to do this as well. I suppose they don't want their good name damaged by Onkyo's hardware goof. I've read this makes a big difference in how the Audyssey software works.
(Mods, please forgive me...)
Details can be found at AVS in the Onkyo 707 thread
and Audyssey thread