[Elecraft] Hi-Cur problem

[Ron W]

Hi,
      I have been building a K2/100 for a friend, and it has all been going 
very smoothly....until tonight.
I had the amp installed and it put out the output it should on all bands, 
but I didn't have the power calibration as good as I liked so I took the 
amp out, removed the shield and set it up along-side the K2 ready to adjust.
Set to 5w, press tune on 40m and the HI-CUR warning comes up. I then find 
it does that on *all* bands EXCEPT 80m.
I take things apart and find it is a problem in the basic K2 ( #4506)
Time for bed here and I am not thinking straight, but that has me bluffed 
at present.
I am assuming the problem is most likely in the LPF as the amplifier must 
be looking into a short or open cct.
Can anyone come up with a thought or two as to what has gone wrong? The 
relays seem to be switching as I change bands.
I have been over both sides of the RF board with a head-band magnifier...it 
eludes me at present!
Cheers.......Ron ZL1TW