[Amps] AL1200, high input swr, all bands

[knormoyle at surfnetusa.com]

some more info

-swapped amp out with al-80b during
contest..everything fine, so cabling etc not an
issue. Tests are into dummy load.

-756 pro II drives the amp. With the rig's auto-tuner
off, swr is infinite. But oddly, the auto-tuner can
get to 1:1 swr. Doesn't help though..no grid or plate
current.

-In standby mode, everything is fine. SWR 1:1 with
autotuner off.

-relays click on transmit and transmit led comes on.

-no visible cooked wires or broken solder joints.  

-read something where someone had a similar problem:
3:1 swr on all bands, no rf output. Turns out the
tube was bad.
How common is this? The manufacturing date for the
amp I believe is 2002. It has the newer relays that
appeared around then.

Is the high input swr a common symptom with a bad tube?

I understand the issues with rtty duty cycles and
thought I was monitoring things well enough.
(actually what's funny is back in 2006 I started a
long thread discussing RTTY and AL-1200 and
temperature monitoring..you'll get a chuckle from a
"AL1200" search here, seeing me thinking about the
issue, and now 4 years later I have a dead
amp..someone could say "told you so" :) ...need to fix..

-Kevin
AD6Z