TC reported train door 'A3' at car 3644did not opened. Staff(CCK) checked and confirmed no train do ors abnormalities. Fault did not recur at subsequent station s. TC reported train door 'A3' at car 3644 did not opened. S ~~~~~ 3644 TC reported A3 train door did not opened. Staff(CCK) confirmed no train doors abnormalities. Fault did not recur at subsequent stations. CE: 3644 check A3 door ops found no abnormality. Door able to open/Closed without difficulty.  Depot to check NL:3 3644 FC 62 registered. (time out 5x) Found roller delaminated. Opr 20raised. Celine 45105 To changeout roller  3644 A3 RHS outer roller delaminated - Replaced. Checked for FOD, checked weater strip - OK. Clean J-rail, Door static test, door gap 63.8mm. Push pull for smooth operation - OK. Door lock switch red mark flush with surface. Anand/Sugu/Alan 45105