a method for measuring load performance of a positive displacement motor test coupon . the test coupon comprises a partial length of a pdm stage and is received inside a sealable test chamber . in some embodiments , the test coupon may be cut from a failed pdm stage . the test chamber is filled with test fluid . in some embodiments , the test fluid may be drilling fluid sampled from a live well . rotation of the rotor on the test coupon actuates rotation of the stator . a braking torque is applied to the stator rotation , enabling evaluation of , for example , fatigue load performance of test coupon . additional embodiments comprise the rotor axis and the stator axis being offset in order to simulate rotor / stator eccentricity in a full size pdm stage .