TC reported train doors at rear M1 car 'B1' did not opened. Staff(ADM) checked and confirmed rear M1car 'B1' door did not opened. Staff(ADM) later isolated the defective train door in closed position. ~~~~~ 1606 TC reported B2 train doors did not opened. Staff(ADM) confirmed 1606 B2 door did not opened. Staff(ADM) later isolated the defective train door in closed position.  1606 B2 door found LHS roller damaged - replaced. Cleaned J-rail/guide rail & no FOD found. Weather strip checked - OK. Door gap 63.8mm, door static test & door push/pull, no wobbling. Function test door operation, no DIR lit up when doors were closed.  Alan/Lee PT/Kamarul/Shafie 45123