[Yaesu] FT990 lost transmit

[Robert Redmon]

I used my 990 to work the 6O the other evening on 80; every thing was fine. 
The next morning, I turned it on and there is 0 output on transmit. 
Everything else seems to be working fine and it switches from rx to tx 
normally with all of the metering functions and panel lights doing what they 
should.  Anyone have a clue what may have happened as it sat over night?