[Elecraft] W1 - no autoscaling

[ON4WIX]

Hi all

I just finished building the W1 wattmeter kit. All went fine without any 
problems.
The part "Checkout and Calibration" (p9 of the manual) was spot on. I have 
4,50V DC at TP1 and >1Meg-ohm across the battery terminals.
First power-on test went flawlessly - The FWD leds blinked, then the SWR 
leds, then the 1,4 / 14 / 140W scale leds.
Then things went acting funny. Powering the W1 from my MFJ 4125 power supply 
and running my K3 into the W1 and terminating into a known good dummy load I 
get perfectly accurate power and SWR readings when running no more than 1,4 
watts. However, the W1 does not autoscale when my K3's output power goes 
above 1,4 watts. Whichever power I run, the W1 keeps showing the 1,4W green 
led and I get full scale FWD power readings.
I have also tested the W1 running on a 9V battery and I get the very same 
results.
The manual says that U4, running FW 1.05, should take care of autoscaling. 
but apparently there's something wrong here. The funny thing is that the SWR 
reading seems to be fine. Using 1W, 10W and 100W show consistent SWR 
readings.
Any thoughts on where I should look first? As stated before, the lowest 
power level shows perfectly accurate power/SWR readings.

Thanks for any help

Glenn ON4WIX