I know this info. is late in coming, but , whenever you work on anything you have to disassemble before you can repair it..
no matter if it's a lamps bulb socket or a TV set.. get out your camera and take pics of ALL you're doing, you probably wouldn't be in a pickle, as you are now . I looked all through my Stihl info , NOTHING on your model, sorry !! Maybe another member can help,
Stihl is captive with their documentation, EXTREMELY tough to find much info. online ..BASSTURDS in my book !