EB applied departing BGS WB, DIR indication illuminated at front M1 car. ~~~~~ L3 1517 B3 door was found isolated & latched. Normalised the door isolating cock & function check the door. Found the door was closing very slowly during closing operation. Checked the door track for any FOD - OK. Readjusted the door close speed. Function checked door open/close operation - OK. Performed door open/close cyclic operation for 20 times - OK. Resealed 3517 DIRBS.  Lee KH/Koon PL. 19/01/2020. L3 1517 B3 door push/pull gauge test about 12kg. Removed bracket from individual door leaf & test about 4kg. Door leaf rubber checked - OK. No FOD found. Re-installed bracket & test B3 door again, about 10.2kg. Door operation test & door gauge test - OK. To replace 1517 B3 door actuator as preventive measure.  Selvan/Anand/Lee PT. 20/01/2020. L3 1517 B3 door actuator swapped to 1517 A3 door & replaced    manifold on 1517 B3 door as instructed by EMM Jefferson - Done. Function test on both doors - OK.  Selvan/Lee PT/Anand. 21/01/2020.