It depends on whether the problem is actually the starter motor, or the more common fail on these engines, the starter clutch. If it's the starter clutch, to do it correctly you need to pull the alternator cover (which means pulling the front sprocket cover as well) to access the rotor and starter clutch sprocket together. You can pull the rotor out of the timing cover but it's tricky to get the rotor back onto the starter clutch sprocket without rollers, springs and caps coming out of the clutch assembly.