TC reported Rear M2 car B1 door did notopen. SM(BGB) confirmedRear M2 B1 train door did not open at BGB SB. SM BGB and SM KRJ unable to isolate the faulty tr ain door. SM KRJ paste the faulty train door sticker. TC rep ~~~~~ 3610 TC reported Rear M2(2609) car B1 door did notopen. SM(BGB) confirmed  Rear M2 B1 train door did not openat BGB SB. SM BGB and SM KRJ unable to isolate the faulty train door. SM KRJ paste the faulty train door sticker.  FC920/926/010/016. Found 2609 b1 RHS door outer roller damage, changeout both door to iron black roller. Mating ok, Push/pull, DLS, DLD, Door cyclic amnd door static test ok. Done by Rizman/Koh 27.02.2024