Seems I heard they weren't supporting really old units any more.
I have an MX-385 in my plane. When my voltage regulator failed in April last year and fried the radio, I sent it to TKM and they still fixed it. Turn around was about 4 weeks from the time I shipped it until the time I got it back. If you need to contact them, send them an email and they usually respond within 24 hrs.