I ran across this Ebay auction
http://cgi.ebay.com/1935-MILLS-NICKEL-5-CENT-SLOT-MACHINE-UNRESTORED-WORKS_W0QQitemZ200378524329QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item2ea77da2a9&_trksid=p3286.c0.m14
In it, the listing claims that the series of 6666666 stamped all over the machine is an
INDICATION OF OWNERSHIP BY THE CHICAGO CRIME SYNDICATE...
Interesting!
Has anyone else ever heard of this method of marking your turf so-to-speak?