Thanks for all the responses
The help desk at Arai finally e-mailed me back after more than a month and a nasty e-mail as a follow up to my initial request.
My local dealer where I bought the helmet could not get the part. I was at the shop while the parts manager called a couple of his distributors with no luck.
If Arai doesn't come through I will try the sources you all have provided.
I discovered this web site after buying my K12 two years ago.
I appreciate the sense of community and support of the members here. It has made having a BMW a much better experience. I do all my own maintenance and have gotten great help and lots of good "how tos" from here.
Thanks again and happy holidays!
'75 Norton Commando