[Premium-Rx] WJ URR-74 (WJ-8718A) issue

[fintronics .]

Reveived my  URR-74 last night.. what a beautiful receiver!. Just about
mint condition, incredible internal construction... While inspecting the
inside, I noticed one of those nicad battery modules soldered on to one of
the plug-in PCB's. The 4 pins were green with corrosion as were the pads on
the solder side of the board. Quite the pain in the butt to remove and I
spent quite a bit of time cleaning up the mess on both sides of the board
but now the battery module is removed and the board is cleaned up with no
open or corroded traces.

Since this receiver has no microprocessor, I'm wondering what the heck a
battery backup/module would be used for? There are no memories, etc...
Figured I'd power it up without a battery and see what happens.

So on to powering it up....It didn't come with a power cord so I powered it
up with a line cord/alligator clips to that 3 pin rear panel connector.
Headphones, outside wire antenna... fired it up... It's working! ....
Switches and pots are very dirty but I'm hearing signals, all modes, all
filter positions working... but then.....

I noticed the strangest thing while tuning across some SW and AM BCB
signals. While tuned to an AM BCB station on 840khz, I noticed what appears
to be an image of that signal exactly 20khz down from 840khz.... and here's
where it gets strange... While tuned to the image signal at exactly 820khz,
if the tuning is moved even 10hz above 820khz the image signal disappears!
completely!.... but if tuned at or below the image at 820khz, the signal is
there, as if only receiving one sideband of the AM signal... This happens
on all AM signals regardless of band or frequency....

What the heck?... could this be related to the missing battery? (doubtful),
.... I did notice when I had the receiver open that some of the SMA coax
interconnect cables were loose... ... maybe this is a problem with
frequency data to the synth getting corrupted?.... don't know...

Any ideas? where to start looking?.

Thanks...

Glenn