The guaranty is a contract; you may sue on it to enforce it. You would file a lawsuit in county court, to enforce the guaranty and seek payment under it. If the borrowers have no assets and little or no income, however, as a practical matter, you may not be able to recover anything, though future receipts may give you a mechanism to do so. You could seek injunctive relief under an order to show cause at the same time as you file the lawsuit, seeking a court order requiring the borrowers to deposit $70k of their receipts into a court account, pending resolution of the lawsuit. If you win the suit, you would then have the money released to you.