The nut secures the clutch cover and the guide bar on the studs of the Partner 350 chainsaw body. It holds the bar in the correct position.
Replace it if the thread is stripped or the flats are rounded: such a nut will not let you tighten the bar properly, and the chain will start to derail. Choose by the thread of the studs on your saw.
It is best to do the work on a cooled engine with the ignition off, and to tighten the fasteners without overtightening, so as not to strip the thread in the body.
