From inside (document excerpt):
PARTS LIST NO. DATE 530163180 Replaces 530163180 — 3/07/07 r PARTS LIST Note: Illustration may differ from actual model due to design changes CHAIN SAW MODEL(s) MAC CAT 441 PAGE NO. 3/04/08 1 27 26 42 44 45 46 43 41 40 TYPE 1 All repairs, adjustments and maintenance not described in the Operator’s Manual must be performed by qualified service personnel. 35 31 30 29 28 23 WARNING 2 Kit–Oil Check Valve Ref.