Dave,
I've got a Radiant myself, great radio. In fact, all I fly is Airtronics. I've sent many radios in for service and trust me, it's well worth it. In fact, I sent my Radiant in last year because of the very same reason. I had broken the last section of the antenna off. I sent it in for replacement of the antenna, plus the receiver had been in a crash. Anyway, they replaced the antenna, did a complete check of the radio including output test, AND cleaned it off completely (it looked new when I got it). They did this all for less than $50 (US). Trust me, the piece of mind you'll have when you get it back is well worth sending it in.

Hope this helps

Ken