There may be a link to a service manual or other product guides for early PowerBook G3
and before, online in some archives; there used to be more at LowEndMac.com years ago.
Here's a site with a few manuals in PDF you can read without downloading, or save offline;
near the edge of this one, when viewing content, are links to other manuals for same one.
The main page appears to offer other ones for different products.
http://www.manualslib.com/brand/apple/laptop.html
• PowerBook G3 User Manual, archive:
http://www.manualslib.com/manual/427686/Apple-Powerbook-G3.html
Perhaps some of the users of these Apple discussions would care to share experience of
using their vintage and obsolete portable Apple products in a technically supportive way.
My most vintage was a first edition white iBook G3 500MHz 12-inch, that I repaired and
sold to an older guy who'd never owned a computer before. I also provided 2-yr support.
Anyway, hopefully you have a good time with your Macs. My dad is over 90 y/o and has
used Mac computers in his avocational and professional tasks since the early 1980s.
Good luck! 🙂