3557 during PM found air leaking from Au ~~~~~ 3557 during PM found air leaking from Au     Checked and found #3557 air leaking from auto coupler cylinder B/S. Replaced Auto coupler cylinder O-ring ok.Carried out auto coupler function test ok.No further aira leaks observed from #3557.Carried out air leak test,0.5 bar/5min. Done by Joshua/Koh B.S. 11/11/20