I guess I just joined the club too. I have a 300C AWD 2005. My Nav knob just broke 3 days ago while I was entering addresses before going on a trip. The 8 way joystick came loose to the touch, won't (turn) zoom in or out and only work at 5% by pushing in hard but won't do left nor right. It doesn't click for me "like the other guy said". I went to the dealer and after 3 hours of work on it, they told me I needed a new Nav System. At a $1000 or so plus labor I decided to investigate. There are few entries on the "LX forum" site, few on our site "300C forum" and this one has pretty good info.
Jeep Grand Cherokee WK - Navigation Radio. It's on jeeps but it's the same NAV as the 300C. Just Google it (
300C joystick) and you'll get several hits.
My dealer told me to contact Chrysler Customer Care and see what they have to say. I called them, they looked into it and called me back few hours later with an answer. If I purchase a new one (Nav System) from my dealer plus installation, I will fax the bill plus info to Customer Care and will look at my case and probably assume some of the cost or all of it (I don't know yet) for the new replacement. They won't accept any purchased outside dealers like eBay etc. So I ordered a new Nav today. It should arrive within a week and it takes 1 1/2 hour to install they say. I have to pay in full first and claim the refund or partial refund (if accepted) through Customer Care.
I'm in Canada so for me it's Chrysler Canada but it might be similiar for the US. It's worth a try.
For the Canadians >>> Chrysler Canada Customer Care telephone # is: 800 465-2001.