This article is from the Pinball FAQ, by Andy Oakland sao@REMOVETOREPLY.mit.edu with numerous contributions by others.
For guides to maintaining machines, you can try the following:
"The Pinball Lizard" sells a series of reprinted technical magazine
articles which are the best reference I've seen for fixing solid-state
home pinball machines! It's the "Joy of Cooking" for pinball owners.
Can be ordered from email@example.com.
Pinball Troubleshooting Guide, Russ Jensen. For upkeep of electro-
mechanicals. Can be ordered directly from author; $20 to
1652 Euclid Av, Camarillo, CA, 93010.
"Pinball Machines: How they work & troubleshooting," Norbert Snicer
ISBN 0-646-11126-4. Available from the author for $40 Australian.
Norbert Snicer, PO Box 622, Randwick NSW 2031, AUSTRALIA.