....good info, thanks!

I turned on the switch briefly and I could hear the pump motor run! The
pool room has the following equipment:

Nautilus NS-48 DE filter tank (probably ok, a bit of corrosion on the
outside)
Aqua-Flo pump with Gould E-Plus 8-151782-02 motor (turns on ok)
Wahlds pool heater (severe rust, probably doesn't work, also rarely used it
when I was a kid)

If I take on this project "at the bare minimum" what I would have on my
to-do list:

Empty dirty water and acid clean plaster (found 3 bottles of muriatic acid
in the pool room)
Fix crack running down side of pool
Refill pool and flush out debris from lines
Replace burned out underwater light
Replace pump mechanical timer on wall (rusted out)
Replace any worn parts inside DE filter (seal, filter fabric?)

No re-plastering for now.

I wonder if I'd run into an expensive surprise or if this could turn out
simple. hmmm