When sourcing second-hand equipment, prioritize structural integrity and mechanical functionality. For cardio machines (treadmills, ellipticals), verify the motor horsepower (continuous duty) and the mileage or hours of use on the console. For strength equipment, inspect the welding points for cracks, the thickness of the steel frame (minimum 3mm/11-gauge recommended), and the condition of cables and pulleys. Ensure that all wearable parts like belts, decks, and upholstery have been replaced or are in Grade A condition.