Train A1 doors at car 1512 were not proven closed. TC recycled train doors twice - ok. Fault did notrecur at subsequent stations. Train A1 doors at car 1512 we re not proven closed. TC recycled train doors twice - ok. Fa ~~~~~ 1512 A1 train doors were not proven closed. TC recycled train doors twice - ok. Fault did not recur at subsequent stations. Fault recurred at SIM2. Staff(TNM) confirmed 1512 A1 train door gap. Train doors isolated at BDK2.(L3) L3 1512 A1 door checked/found LHS/RHS inner & outer rollers damaged - replaced with new rollers. Conducted open/close doors operation & door no wobble. Checked no FC & suspect FOD caused the door fault & FOD was dislodged when staff assissted to push close the door. DIR was activated during train in motion, looking at ER. Postulate pax was leaning against the isolated door. Preventively serviced the J-rail & guide rail on #1512 doors. Preventively replaced #1512 A1 door actuator & manifold. Side finding : Found #1512 A1 door rollers having slight pitting & replaced. Conducted 10mm/20mm gauge test - Passed. Door static test & door open/close speed test - Passed. Door cyclic test 20x & door operation was smooth with no abnormalities.     Daniel/Aliff/Chan SW/Wong WK/Aqil/Shamil/Akira 45461