Train doors at Front DT door #1 were notproven closed. TC recycled train doors four times - ok. Fau lt did not recur at subsequent stations. TC then reported TI MS showed Front M1 door obstacle detected. Staff(BGB) checke ~~~~~ 1608 Train #1 doors were not proven closed. TC recycled train doors four times - ok. Fault did not recur at subsequent stations. TC then reported TIMS showed Front M1 door obstacle detected. Staff(BGB) confirmed 1608 A1 door did not open at all.  1608 A1 LHS door roller found damaged. Replaced the door roller. Cleaned the J-rail. Function check door operation & no DIR lit up.  Alan/Lee PT/Shafie/Kamarul 44941