I dropped off a exmark 48 ztr last week for a busted hydro belt. Other than that, everything was running perfectly. Called in today to check and see if it was ready, the mechanic tells me he fixed the belt, also replaced a dead battery (wasnt dead when we fired it up at the shop on Friday) and says the starter is making a horrible knocking noise. (also wasnt there on friday) If the key is left on, does that drain the battery, and can that affect the starter? im going to pay them a visit in the morning. thanks.