Train doors was not proven closed. Opened and closed a few times to no avail. TC tripped DCB to no a vail. ~~~~~ Train doors was not proven closed. Opene     Downloaded and checked ER found train DIR to be inttermittent and DIRBS was activateed in #3554 (leading cab) Checked and found #3553 B/S cab door handle unable to spring back to close(normal) position after opening.Further check found FOD inside cab door mechanism hindering movement of cable when door handle operated causing door tongue to be unable to extend freely outwards and door to be closed but notpositively latched when handle is released.Removed FOD and service #3553 B/S cab door mechanism.Preventively re-rigged cab door based on approved MRC criteria.Conduct door cyclic test and tug test no triggering of DIR wheen door is fully latched.#3554 cab DIRBS normalised and sealed.DCB normalised. Done by Johari.  08/08/22