TC reported rear DT car 'B1' was closingslowly then the rest. SM(TAP) feedback after monitoring for 3 stations that the rear DT car 'B1' door closed halfway th en closed fully after 3 seconds. SM(RFP) isolated the faulty ~~~~~ 3623-TC reported rear DT car 'B1' was closing slowly then the rest. SM(TAP) feedback after monitoring for 3 stations that the rear DT car 'B1' door closed halfway then closed fully after 3 seconds. SM(RFP) isolated the faulty.  3624 ER D/L - Done. Checked 3624 B1 door checked with push/pull gauge at 12 kgf. Cleaned 3624 B1 door J-rail - Done. Push/pull gauge test at 6.8 kgf - OK. Performed door cyclic operation about 20 times - OK.  Selvan/Alcus 43959