First of all to aid in your Stihl MS 380 chainsaw switch repairs or servicing work , head over to the manuals section of this website and view or download a free parts list HERE
This clearly shows all the chainsaw components in exploded diagram view along with parts numbers incase you need to buy any parts. View or download the full service manual also to be found in the manuals section under Stihl MS 380 (MS380). Or use the search button at top of page (magnifier icon)
Some handy tips on repairing your Stihl MS 380 chainsaw on off switch worth considering is the function of this switch. The switch works by shorting out the coil to ground, if the switch is not working then you may have a broken wire,defective switch or kill wire may be disconnected at the coil.
Make sure that the connectors on the coil are clean and free of corrosion, it’s like a vehicle battery where if you have any corrosion around the metal contacts, it will not make a good electrical contact.