The Murray doesn't have automotive style clutch plates. It is belt driven and steping on the clutch/break just moves a pulley to place slack in the belt and allow the mower to remain still. It could well be that the belt has streached and worn to the point that it will not tighten enough to move. suggest you check your owners manual and see if there is an adjustment on the idler pulley which will create greater tension. Otherwise, I would consider replacing the drive belt.