[R-390] Where do I begin?

[r390]

OK...here's my story.  About 10 years ago, I was given an R-390.   What 
a great radio, it worked awesome, and I
really love that radio.  Well a few years later, signals got real weak, 
and then suddenly they were gone.  I could hear
a hiss and it would get louder as I turned up the gain, but the signals 
were gone.  Well, as luck would have it, a divorce, a job change, and a 
move got in the way, but I always lugged that radio with me knowing that 
"someday" I'll fix it up.  Well, the day has arrived!  I have a nice new 
home, a great shack, and now I want to get those signals back!
I'm not a complete dope when it comes to working on radios, but I've 
never worked on the R390.  I'm in the process of trying to find a 
manual, but in the meantime I thought I would appeal to you guys to see 
what sort of advice you could send my way.
By the way, one of the uses I had for the rig back when it was working 
good was to feed a homebrew RTTY demodulator which drove an old Model 28 
RTTY machine.  Hmmm I still have the demod, and the RTTY machine.  Yup, 
I lugged those along too.
So, if anyone has any advice at all, I'd be most grateful.

Thanks es 73

Jim KA1EUI