TC reported that obstacle detected at car 1652 'A2' doors. Fault self-cleared when train departed fr om station platform. Staff(KRJ) checked and confirmed the pa rticular train doors were not fully open but pax's movement ~~~~~ #1652-A2 door checked J-rail and door guide rail. Found sticky substance at door guide rail, removed. Serviced J-rail and door guide rail. Checked door post weather strip ok. Pull/push 7kgf, ok. Door mating strip 63.5mm ok. Carried out door cyclic test ok. Door opening/closing time within criteria. Done by Joshua/Zulq/Koh.  28/12/20.