TC reported TIMS showed fault indicationat Front M1 car 'A4' door. TC feedback no abnormalities at CCK SB. ~~~~~ T202 3604-TC reported TIMS showed fault indication at Front M1 car 'A4'door. TC feedback no abnormalities at CCK SB. Fault recurred at KRJ SB. Staff (YWT) feedback the train door did not opened at MSL and WDL, later isolated the train door 'A4' at ADM  From TIMS observed car 1604 FC082 - Saloon Door A4 OPE occuring many times on 17/2/24 and on 18/2/24 (7:44AM). In depot, door was unable to open automatically; door lock device had an abnormal clicking sound. The solenoid was unable to lift the vertical slider to release the lock pin to unlock the door. Changed out DLD and function tested ok. Rectifications 1) Replaced the door lock device. 2) Cycled 20x ok, door operation was smooth with no abnormalities. DIR and DMI able to light and extinguish. 3) Manual push/pull resistance ok. 4) Door rollers had already been changed out to black iron rollers (FW). 5) Door static test / door speed ok. 6) Ensured DLS lock nut and other fasteners were secured. 5) Found and removed sticky FOD (side finding). Serviced J-rail and guide rail. 1604 A4 DLD Old SN: C151BDL145055 New SN: C151BDL15Y026 Notification: 2572235 Done by: Jack/Koh/Rizman 18.2.24