<human>: Can you provide a brief rundown of the text in within 3 sentences?

I have a small family check cashing business and a relative cashed a series of out of state (TN) bad checks totaling $9,000 dollars. The checks did not clear, they did not have sufficient funds. I'm trying to recuperate as much of the funds without procuring an attorney (not enough money). The customer who cashed the check, not the company who issued it, made some payments towards paying off the debt, but now refuses to pay the remainder. He paid about 60% of the balance before he stopped.

In response I've tried to device of some ways to protect my business from fraudulent checks.  Can I have customers, with checks over say $500, sign a form stating they will take responsibility of the check if it has insufficient funds. Is this illegal or unenforceable?
<bot>: Can a small business require clients to sign a liability form in which the client takes responsibility of paying the negative balance, if the check they cash has insufficient funds.