TIMS showed obstacle detected at car 3625 'A1'train doors. TC opened and closed train doors a few times to no avail. SM(KTB) pushed closed the faulty train do ors for train to depart. Fault recurred at YIS NB and SM(KTB ~~~~~ L3 3625 A1 door rollers cleaned. Replaced LHS door roller due to slightly worn-out as preventive measure. Rechecked door push/pull resistance - OK. Cleaned J-rail as preventive measure. Swapped #3625 A1 DCP (1503W0200015012) with #3625 A2    DCP (1503W0200015007) for monitoring. Performed door cyclic test - OK. DIR/DMI able to extinguish. Performed door static test, all doors timing within criteria. Checked both DT cars DIRBS were normalised & sealed.  Alan/Sugu/Kamarul/Lee PT. 01/09/2022.