TC reported one of the train door at rear DT not proven closed. TC recycle once to clear fault. TC r eported one of the train door at rear DT not proven closed. TC recycle once to clear fault. ~~~~~ 223 3616 TC reported one of the train door at rear DT not proven closed. TC recycle once to clear fault.. CE:Monitored 3615-all train doors proven closed."  L3 FC-993 CLE TIMS showed FC993 3615 Saloon Door B4 CLE occured 7 times. From ER, from 16:22 - 16:23 TC cycled doors 2 times before train doors were proven closed. From ER, from 16:30 - 16:32 TC cycled doors 4 times before train doors were proven closed. From ER, from 16:36 - 16:37 TC cycled doors 1 time before train doors were proven closed. (Took around 40 seconds for DIR to extinguish, Staff(SBW) assisted to push close rear DT "B4" door) From Fault Trace, the doors were stuck with corresponding gaps of 104mm,    88mm, 48mm, 88mm, 112mm, 104mm, 80mm in each cycle. In depot, doors were isolated. When doors were normalised, doors were able to cycle without any abnormalities. Scratch marks were found along the guide rail. FOD - Hard candy was found on the guide rail, postulate that FOD has caused the door to be jammed during closing operation. Evident from FOD being grinded with sharp edges. Proceed to remove FOD from guide rails and proceeded to cycle doors. Found B4 RHS inner main roller damage and outer guide roller worn out to C/O. Mating strip, push pull, DSS, DLS red line present & lock nut secure. Door cycle and static test ok. B4 RHS inner coller c/o with bloack roller both door. Done by: Jack, Koh, Sanip, Khairudy, Daniel. 24/05/2024.