Oh I got this!!!  The sound board may need repair.  Common among the G3 powerbook lines.  Its sound port solder lets go, and is in a soldered down cage around it.  You have to desolder the cage to repair the port and then solder cage back on or the sound will think something is plugged in on boot, even tho the circuit is open (no idea why that is, but it is) and sound on the speakers is disabled.  Its sees the speakers and they are in the list but of course do not work.

Somewhere last year I had a post on this repair.