[Amps] 811A vs. 811H amp power output questions

[Mike & Becca Krzystyniak]

   A friend has a Ameritron 811A amp.  Claims it puts out ~700+ watts into a
DL.  Recently he bought a pristine Ameritron 811H amp.  But surprisingly it
only puts out ~600 watts.  He drops in 4 new tubes and it still only puts
out ~600 watts.  Both amps were being driven at ~65 watts from an Icom
756Pro3

   I looked at the schematics, and aside from the extra tube and the plate
blocking cap being doubled up, I really do not see any other changes.  I
sorta expected the tank "L" values to be changed slightly but that is hard
to tell from the on line documentation.

    Anyone seen this problem before?  Aside from recycling the amp is there
any hope?

Thanks

73's  Mike K9MK