On Tue, 22 Sep 2009 20:26:09 -0700 (PDT), hershey
wrote:

Hi-
I've got a gorgeous Zenith RD7000Y with a 500MDR70 chassis in near
pristine cosmetic condition that plays worse than a $4 drug store
cheapie.

It's the speaker. See article at:
http://www.radiointel.com/nr-d7000y.htm
in the "Disassembly - Routine Cleaning" where he talks about the
deteriorated speaker gasket and fried push pull output xsistors.
They're in sockets, which makes replacement trivial.

Schematics and manuals:
http://www.transoceanic.nostalgiaair.org/

More info:
http://bellsouthpwp.net/p/a/padgett46/transto.htm#Roy7000

Who can I trust this gem with to do a first-rate electronic repair and
alignment job?

Dunno. It might help if you disclosed in what country you reside.
There are quite a few web sites with photos and storied by Zenith
Transoceanic owners. Some might be willing to do the repair or know
someone that can do the job. I once rebuilt a tube type B-600 series
radio. I spent countless hours restoring, only to have it disappear
when I moved residences many years ago.




--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558