I'm not Gene and I'm not an expert. (both proven over time. Marv makes a good point, however I believe you should contact gaming control and appeal your case.

12.070 Redemption and disposal of discontinued chips and tokens
Section 2 (c) "Publication of notice of the discontinuance of the chips and tokens and of the redemption and the pertinent times and locations in at least two newspapers of general circulation in Nevada at least twice during each week of the redemption period, subject to the chairman's approval of the form of the notice..."

The question is, are these valid checks or have they been discontinued? If valid, you should still have a claim to receive payment.

The death of Benny Binion sure has thrown the old chips at the Horeshoe into chaos. He had a cache in the workshop, who knows how many in the safe that was emptied, and who else he may have given chips for payment for services or other habits?

Simple answer, appeal to gaming control.