1981 Corvette Delco radio

Hello:
A Delco radio from a 1981 Corvette came across my work bench. It must
be the top of the line for it's time; it is electronic tuned, and
auto
reverse cassette. Unfortunately, all the stickers for model and
serial
numbers have fallen off the radio's case.
The complaint is hiss, but no tuning, no display, no music.
I applied 12Vdc, and the complaint is correct. The display is dark,
and only a small hiss in the speakers.
I actually repaired Delco car radios back in the late 1970s when I
worked for a local service shop while in high school. I have
forgotten
much about these, but remember that for the most part, Delco radios
were reliable, and generally simple to fix.
With this radio, I am not sure where to start. A schematic wouyld be
helpful, but I do not havethe model, and do not know where to get
schematics.
Any advice, and assisatnce is appreciated.
Thanks,
Bill