Here are some instructions for taking it apart:
http://www.arboristsite.com/chainsaw/23064.htm

If you still want to bother after you read that (I wouldn't), here is the illustrated parts list (go down to 21527):
http://www.mymowerparts.com/pdf/McCulloch-Parts-Service-Repair-Manuals/Gas_Powered_Chain_Saws/