[Elecraft] KAT100 IN EC2 ENCLOSURE

[Jerry Ford]

 Good evening all:
I'm looking for some advise.   My KAT100 / KPA100  are in an EC2 enclosure next to my K2.
I was changing bands this evening and neglected to changeantenna's when moving from 80 to 40 meters.
I hit the   " TUNE "   on the K2  and my KAT100  triedto tune.  It ran through the scale a couple of times beforeI could shut it off.
Now when I hit the "TUNE"  button,  the radio goes intotransmit,  but the tuner isn't tuning anything.   Normal operation the tuner would tune and go back to receive.
It doesn't change back to receive unless I hit the tunebutton again.  SO,   the tuner quit.
I remember reading about a transistor that fails and causes this issue but I don't remember which one it is.
SO,   looking for some information.   
Any idea's what I'm looking for ???
Thanks:      73            Jerry             N0JRN