[R-390] A few SP-600 questions

[Jack Antonio]

The universe decided I needed an SP-600-JX-17, so one
is now gracing the workshop.  An initial inspection showed
disc ceramics instead of BBOD caps, and no obvious B+ shorts
or any major DPO mods (DPO=dreaded previous owner)
so I fired it up, and it seems to work pretty decently.  The BFO center
frequency was way off, but a quick tweak solved that, but I'm sure
it needs a little work with the test equipment. 

Playing with it raised a couple of questions.

Is the stock power plug a readily available item? Mine came
with a line cord running through one of the vent holes on the chassis
and the power receptacle well taped up.

How stable should the local oscillator  be on 6 meters?  I can tune SSB
on 27 mcs with good stability, but the local 6 meter beacon 
warbles all over the place. SSB would be impossible to tune,
the short term stability is just too bad.  Is this normal, or
do I have a problem to solve?

Is the stock antenna connector supposed to be an 
SO-239?  Mine looks like it has been replaced.

Tried to see if there is an SP-600 group on qth.net, but 
that page is loading super slowly today.

Thanks
Jack Antonio WA7DIA
scr287 at sbcglobal.net