exmark pump or wheel motor

Have a guy wanting to sell me his 2005 exmark, he said right side quit driving all together instead of fixing he bought new
not much of a wrench turner....anyhow he said he would sell to me for $300. Is there anyway of knowing if its the pump or the motor??

You should be able to do a pressure test on the pump, most wheel motors I've seen go bad are leaking at the seal.