Train doors at Front DT car were not proven closed. Staff (CCK) checked and confirmed that Front DT car, 'A1' door had obstruction. Train door was able to closenormally at subsequent stations. ~~~~~ Downloaded ER and fault trace on PTU 006. Found #3664-A1 door mating strip near door guide rail to be folded causing high resistance during door operation. Trimmed off the folded door mating strip-ok. Checked door guide rail and J-rail ok. Checked door pull/push 7kg ok. Checked door mating strip 63.4mm ok. Checked door rollers, motor current, DCS and DLS ok. Door cyclic/function test ok. Done by Kumar/Jack/Sateesh/Koh. 12/05/20.