When I first got interested in antique slot machines I would bring them home and my wife would always say; “there better not be any bugs in that thing!”. At that time she naturally assumed that since it was old, there had to be nasty creatures living inside it. Being the good husband that I am I would dutifully take the vacuum and clean out the machine before bringing it into our home. What I didn’t know at the time was that some of those machines would still have a bug inside, but the bug wasn’t the creepy crawly kind – but a mechanical bug that was much more mischievous and sinister!
As I started working on machines and restoring them in detail I would run across a strange little device that seemingly had no purpose. It almost looked like it has clamped itself onto the reel bundle of the machine and wouldn’t let go! The first one of these strange little mechanical creatures I found was on a 1929 Mills Poinsettia machine.
Initially while testing the machine I never even noticed its presence – why would I? However after manually lining up the reels to trigger a payout on the machine I would notice the third reel would never stop on the jackpot image. Now it should be mentioned that most Mills slot machines of this era had what is called a 10 stop mechanism – meaning only half of the images you see on the reels are “live” or can actually be landed on. So, after determining which of the two jackpot symbols on the third reel is real, I still couldn’t get the machine to land on it, even when I held the reel in place!
So why in the world would Mills make a machine that wouldn’t land on the jackpot symbol? The answer is they didn’t, but other people would make a clever little device that could be installed inside the machine in seconds – eliminating those pesky jackpots from ever being hit on the machine! With about 2 cents worth of metal the machines odds of hitting a jackpot would go from 8000 to 1 to zero, and no one playing the machine knew the difference.
As I worked on more antique slot machines and then made it my full time profession in 2005 I would occasionally run across these nasty yet interesting little devices, and still do today. During that time I also ran across vintage gambling supply brochures and books. In some of these sales brochures they would openly list for sale “Percentage Devices”. Well that doesn’t sound too threating or something that sounds morally questionable does it? As it turns out those “devices” were bugs – small parts that once installed would magically not allow specific symbols on the reels to ever be landed on – how rotten!

Interestingly enough, the industry trade suppliers sold these without really trying to hide it. Granted, coin operated machine operators of the day didn’t exactly advertise to the general public how their machines worked or how easily they could be manipulated to lower the winning payouts.
During the Golden Age of slot machines (1931 – 1942) a vast majority of slots were not being used in casino’s where rules and tight scrutiny were present. Most slot machines were found in gas stations, bars, clubs and other common places men hung out at. These places didn’t have state gaming commissions checking their machines for proper payout percentages.
Sometime last year I had the pleasure of briefly talking to an elderly gentleman who operated slot machines in California in the 1940’s and 1950’s. He asked me if I knew what an Oregon Boot was? I didn’t know what he was talking about until he described to me a bug! He said the “syndicate” he was working for would use them on all their machines. The “syndicate” he worked for apparently didn’t care if they were screwing the players. I got the feeling these little “Oregon Boot’s” were a fairly minor ethical infraction compared to other stories he would go on to tell me!
So, the next time you are playing your favorite antique slot machine and notice those darn jackpot bars never lining up – you may want to remember my wife’s first rule before bringing a slot machine in the house – MAKE SURE THERE ARE NO BUGS IN THAT THING! Ha ha

This Manual is in a PDF format which shows procedures for adjustments, repairs assembly and disassembly. This is a super find! Well illustrated and detailed manual for Adolph and Arthur Caille, The A C Multi-Bell Slot Machine. Click on the picture to view the machine this manual is used for. Instant download after payment.

This Manual is in a PDF format. Instructions for Adjusting Caille Superior 'Jack Pot' Bell Machines. This is a 24 page manual for the mechanical Caille slot machines. A great small manual on this machine. Instant download after purchase.

This Manual is in a PDF format. An aftermarket manual. includes information on machines like Grand Prize, Reserve, Dough Boy, Cadet, Commander, playboy, and others. About 30 pages. Instant download after purchase.