Is My Onkyo Receiver's Tuner Dead or Just Playing Posum?

I lost the AM/FM tuner in my Integra DTR9.9 (vintage 2008) a long time ago. It just stopped working one day. Totally silent. So dweller, I don't think you're crazy. I also live in Las Vegas (not that it matters to this discussion). I was using the XM mini-tuner functionality on the DTR9.9 and it was flaky as well. I would lose the option to select the XM tuner from time to time and I would have to do a full reset on the receiver to get it back.I bought a used Integra TUN3.7 standalone XM/AM/FM tuner. The XM worked fine on this unit. But the FM tuner would flake out after it warmed up for about 20 minutes. It would switch in and out of HD radio mode and make a lot of noise making it un-listenable.Finally I bought a Sangen HDT-20 for AM/FM listening and it is working well with a dipole antenna stuck to the wall of my living room.

 Yes, it's funny the thing just conked out. I really enjoyed the digital-radio feature of this receiver. I may be rearranging my HT room which will let me take the Onkyo outside for a clean signal. Then I'll know for sure.
 P.S. In Vegas, I had a clear line-of-sight to the Black Mountain transmitters (in Henderson). Regards

FWIW, I doubt signal strength is the issue.  Even the weakest signal should unmute the FM muting.

I have a different problem with my Integra DHC80.1.  The Internet Radio has stopped working, after working fine since new 8-10 years ago.  Everything else works fine.  Any ideas anyone?

I tried using the radio next to a window, with two antennas (AM/FM) and zilch, nada, nothing. Tried headphones -nothing. The tuner seems to be working so the amp section must be bad (or it's something simple I haven't found yet). Still works great with movies and TV, however.