TC reported Front DT car 1st pair traindoor did not open. Staff(CBR) checked, confirmed Front DT ca r 1st pair train door did not open. ~~~~~ 3634 TC reported Front DT car 1st pair train door did not open. Staff (CBR) checked, confirmed Front DT car 1st pair train door did not open.     Check no FC but confirm 3634 b1 door did not open. B1 LHS door roller damage. Replace done. DLS present, Lock nut secure and DLD rubber cushion ok. Mating strip and Push/pull within criteria. Function check ok. Door cyclic test ok. Done by Rizman/Omar 20.12.2023