David,

I am not a lawyer, so what follows may not be 100% legally correct. But, it is not difficult to understand at a moral level what is wrong with altering casino chips.

Fraud occurs when someone does not disclose information that could have a negative effect on a possible transaction. The example you give does not extend itself, even remotely, to "alterations" to casino chips. People repair clothing regularly, it would be an exception to repair clothing for the purpose of fraud. However, casino chips are not regularly repaired for any purpose other than fraud. If someone repairs a casino chip for someone who is a regular seller of chips, the repairer knows or should know that there is a possibility that fraud may occur. And thus the repairer is a party to the fraud.

However, all this is moot because of the Hobby Protection Act. The HPA makes it illegal to alter numismatic items (including casino chips) without marking the item as altered. It it my opinion, and hopefully the opinion of the courts, that anyone who alters a casino chip without making some non-removable identification of the alteration is in violation of the Hobby Protection Act.