1, the other side if you agree to delay the payment of the tail, you can use the machine as normal, as long as you agree with the other side of the time to pay the tail, there will be no trouble.
2, the other side if you do not agree to delay the payment of the final payment, you refuse to pay, the other side can sue you, and can seize your property (including the machine), then you not only have to pay the final payment, but also bear the responsibility for breach of contract.