Sudden, strange Accuphase FM tuner behavior


I listen to a lot of FM radio through my Accuphase T-100 tuner which has been flawless since I bought it about six years ago. The signal level, as indicated by the signal meter on the front of the tuner, is usually just above 4 while listening to a local station (the meter goes from 0-5). While listening the other day, the music stopped and the signal level went to 1.5. I discovered that if I put the FM muting selector to “1” or “off” instead of “2” (where it usually is) the music comes back but with a little more static than prior to this problem. The signal level is still at 1.5 with the FM muting selector at "1" or "off". What is going on here? The service manual is available here, but I couldn’t find anything that points to the cause:

http://vintageshifi.com/repertoire-pdf/pdf/telecharge.php?pdf=Accuphase-T-100-Service-Manual.pdf
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FWIW I use an Omni directional antennae in my attic (with my T-100) to great affect. I have used to use a multi element FM antenna but found it was a problem re orientation to signals outside of a narrow field. Fortunately though I do not have stations nearby to overload the stations I listen to so an Omni works just fine!
Thanks, Yogiboy. That's something I had not considered at all, but it's totally possible. Moving the antenna is next on my list of things to try. It's just a cheap little dipole taped to the wall behind my rack. I have recently been toying with the idea of buying buying a yagi and attic mounting it, but it looks like that might be a necessity now! The T-100 sounds phenomenal, indeed. I hope quality FM broadcasts never go away.
Something could have changed between the stations
transmitter and your location. It could be anything like a new
building or the landscape ( trees,etc)is blocking the strong
signal you had. Reorient your antenna and see if that helps. If
the other stations are clear the tuner is working fine.BTW,I
had that tuner many moons ago and it was the best sounding
tuner that I have owned !
The signal of the only other station I listen to, whose transmitter is close to the other one, is much higher and closer to normal. I emailed the radio station and they said that they have not changed their power. I'm stumped here.
Have you checked other stations? It is entirely possible that your station has reduced its output signal.