[Amps] FL2100B and 572B damage questions

[Mike & Becca Krzystyniak]

   I picked up a FL-2100B amp that allegedly had 200 watts drive applied to
it.  The owner said it was toast and wanted me to put new tubes in it.

   For grins I powered it up.  The tubes did light.  When I keyed the amp
with out drive, there is 75-100mA of idle bias current.  And I noticed there
was an odd hissing sound.  Upon careful examination the hissing was RF
arcing across the loading cap.  In fact it will do this with the band switch
in the 40-10M positions, but not 80m. There is some dependency on the
position of the loading cap the get the arc but in most cases it is
mid-range.  Note: The parasitic chokes are intact and have no sign of being
heat stressed.
  
   Am I looking at some subtle tube damage that was the consequences of
blasting the amp 200W for a brief period?  In my dealing with parasitics,
there was always some distinct surge in plate current with a parasitic peak.
I'm not seeing that.  So, am I correct in thinking this is not a parasitic
as there is no visible surge in plate current associated with the
hissing/arcing.  But what else could it be?

   Before I drop my spare set of tubes into this amp I want to make sure
there is little chance of collateral damage.

   Thoughts and comments would be appreciated.

73's  Mike K9MK/5

PS: Because of the arcing, I'm guessing it would be prudent to replace the
loading cap. Anyone have a lead for a loading cap for a FL2100B?