[Amps] tubes

[carlseye at tampabay.rr.com (carl seyersdahl)]

 This is something I should know , but it seems to have   escaped my memory
bank. !!
 I have several 811A's and all of them have oblong shiny spots on the
plates, and they all glow a dull red under full power in an AL811 amp. Are
these tubes defective ?? I was running about 70 watts input and about 600
watts out and all of the tubes show the same symptoms. !!! Thanks for any
replies.
 carl / kz5ca       (I g = 90-100 ma.) (Ip 650 +-)