Basically, you said, 'Once a poker game organizer, always a poker game organizer'!
You also said: "The case against Keller was dropped on Sept.10th 1936. CDK chips ordered about a month later." Since the case was dropped for lack of evidence, perhaps the Police mistakenly destroyed the evidence (some yet to be identified chips) from the bust the year earlier, upon which time Keller knew he then needed new chips to continue his vocation and he placed the CDK order.
Something to consider, or look at, is an earlier chip order(s) in Keller's name, or initials with Mason, or another supplier.
Anyway, great research and presentation!