should the wheel motor be replaced when ever the pump is replaced? we've got an ex-mark mower that had a bad pump so I replaced it in April. 3 months went by the new pump went out so we sent it back and got it warrantied and replaced. 1 1/2 months goes by and this new hydro pump is starting to go. it's making a loud growling type noise just like the other 2. I called Stens (who we get the pumps from) and talked to their technical support guy. he said the hoses, pump, and wheel motor need to be replaced together (close to 1,000 dollars). Does anybody have any insight to this?