Contact Paul at AZPETE on the Irv2 forum. He works for HWH and can answer your questions. His email is email@example.com
and his phone number is 602-549-3638. He is a Commercial Member and has posted that his phone is always on, and if not answered, leave a message.
He has helped others on this forum, including me, and I am sure he can help you.
Another source is Chuck Stuarts at Stuarts Service 1-800-826-6267 or 574-262-0225. HWH Replacement Parts - Stuart's Services