TC reported DIR failed to extinguish after all train doors proven closed. TC opened and closed traindoors a few times but to no avail. TC opened and closed Cab door 'A' side once - ok. ~~~~~ TC reported DIR failed to extinguish aft   Checked and confirmed 3501 A/S cab door movable latch mechanism missing one screw - replaced missing screw, checked overlap satis Checked all cab doors on both ends latch mechanism - ok Function tested all cab doors - satis, DIR lit and extinguish accordingly. N.AMUTHALIB/ZAINI/23.10.23