[Elecraft] Excessive SWR Faulting KPA500

[k2te at juno.com]

I discovered a problem this afternoon where the KPA500 is faulting on 20,
17 and 12 meters.  Set up here is the K-line, K3/KAT500/KPA500. 
Everything had been working fine until this point.  I get a hard fault
(error code 9) on the three bands which means excessive SWR even though
it has tuned fine before switching from standby.  Antennas: 6BTV vertical
and Inverted Vs for 17 and 12.  The Vs are fed from a common point.  The
KPA500 works fine on 80 thru 10 on the 6BTV except 20 of course.  I tried
turning down the power when on 20 (via the K3 drive) but the SWR runs up
and faults.

I checked the Elecraft website but no schematics for the KPA500.  My
guess is the LPF units for the bands in question have gone TU.

73 de Ed