The brake system on a second hand tractor must be rigorously tested for operator safety. Perform individual wheel braking tests at low speeds to ensure both sides engage evenly without pulling. Spongy pedal feel or grinding sounds usually indicate worn brake shoes, air in lines, or depleted hydraulic fluid. https://linkgeanie.com/automotive/how-to-find-a-second-hand-tractor-serial-number-when-it-s-missing