Leon's pinball - Equally informative and the best to CLAY's pages. 

Clay's Pin Monkey pinball repair website. If you are to only visit two websites, make Clay and Leon's website the two.

Mr. Pinball Repair tips - pretty good archive of tech tips

Ring of Pinball List - The best of the best - The list has shrunk from 177 to just over 100. Dead links, owner change, and better standards has weeded out some 70+.

Download cross references, etc. - A one stop for semiconductor cross reference/replacement guide software.