Marshall Fey — Mills Slot Machines: The Complete Service Manual 1906–1969. Spiral-bound, ~68 pages, written by a long-time Nevada operator who serviced Mills machines for a living. Identifies most mechanism parts with full-page diagrams, covers troubleshooting, lubrication, and how to calculate payout percentages. Once §8.1 tells us which mechanism we have, this resolves most of the VERIFYs in Chapter 3.
Scanned original Mills service manuals for related mechanisms: coinslots.com/manuals/mills. Part numbers and photos transfer even where the model differs.
Museum of the Game entry for Bursting Cherry: arcade-museum.com/Slot-Machine/bursting-cherry — dating, census, related models.
9.2 Parts and springs
ibuyoldslots.com/parts — priced catalog of Mills castings and assemblies with part numbers; good for cross-referencing what we photograph.
eBay sellers with Mills spring sets (kicker, payout slide, upper finger, jackpot). Order to a measured sibling (§4.2), not to a name.
CoinOpCollectorForum "Parts For Sale" board — has Bursting Cherry-specific threads.
9.3 Forum references carried over from earlier revisions (not re-verified)