[Hallicrafters] SR-2000 Low Output Problem

[w9ran at oneradio.net]

Happy Memorial Day to all!

If anyone has been under the hood of an SR-2000, I'd appreciate any
thoughts on my low output problem.  I initially thought the 8122's were
shot but I've swapped in another pair which are supposedly good, and the
results are the same, so I feel I need to look further upstream (which
is good news!).   The driver and other tubes test OK, and substituting a
different 12BY7 produces no improvement.    In TUNE position, I can
barely get enough output to get the meter off the peg, but everything
does peak up as it should.   Once I kick it up toe High Power and crank
the mic gain all the way up, I can whistle up to 400 watts output or so,
measured on a Bird.   On antenna, output is maybe a few hundred watts on
normal voice peaks but signal quality is fine.

I'd really appreciate any experienced opinions before doing a complete
alignment, or more detailed troubleshooting.  I've also wondered about
whether an ALC problem could be holding the output down.  What would
really help is to know some drive levels, for instance at the grid of
the driver and finals, as the Hallicrafters manual doesn't have much
detail.

Thanks for any assistance!

73, Bob W9RAN