[Elecraft] K3s not transmitting AFSK

[Mike Dodd]

Here I am in the middle of WAE RTTY, and suddenly my K3s is not 
transmitting RF on AFSK A. Here's my configuration:

* Built-in USB sound card
* N1MM+ with MMTTY engine
* MODE is set to DATA
* DATA MD set to AFSK A
* PWR is set to 100W
* LCD and MMTTY decode RTTY signals correctly
* TEST mode is off

Everything was working perfectly five hours ago when I turned off the 
rig. Now I turned on the rig again and launched N1MM+. If I press F4 (my 
call) the transmitter keys (TX light is on) and produces RTTY tones that 
I hear and that MMTTY decodes and displays. But no RF comes out of the 
rig. The RF meter has one bar at 0.

Does anyone have any idea what's going on? Should I reload the firmware?

Thanks

--- Mike N4CF