[Elecraft] [P3] P3 woes - repaired but now claims my K3s puts out 873W!

[Dave New, N8SBE]

So, I was the guy that had a P3 display/boot problem recently.

I sent it to the mother ship for repair, and they found that (get this) 
the 12V supply was shorted to the 3.3V supply (eep!).
So, a new(er) I/O board (which contains the supplies) and a replacement 
blown 3.3V LCD controller later, I have an (almost) fully functional P3 
again.

EXCEPT, the TX Monitor function is now funky.  It claims that my K3s is 
putting out 873 (or so) watts!  I've tried both sensors (I had a 200W HF 
sensor on the shelf since I added a KPA500 and changed to a 2KW HF 
sensor), and although the scale max changes on the P3 display when I 
change sensors, it still way overstates my output power.  The KPA500 is 
showing 1360 watts on the P3!

I unplugged/re-plugged everything, did a visual inspection of the TX 
Monitor adapter board under a lighted magnifying glass, looking for 
missing/broken SMD resistors or caps, but so far no soap.

I'm wondering if the new revision I/O board is somehow incompatible with 
the older TX Monitor board, or maybe there is a missing 1M-ohm resistor 
to ground on the I/O board at the sensor connector, or an incorrect 
series resistor value there.

And yes, I sent a note to support, but I haven't heard back, yet.  
Wondering if anyone (Alan?) has any ideas where this behavior is coming 
from.  The wattmeter in both my K3s and KPA500 are working normally.  
It's just the P3 wattmeter that's gone off the deep end, now.

Thanks, and 73,
-- Dave, N8SBE