Pax feedback to staff(NEW) whistling sound from train. Staff(DBG) checked and heard faint air seepag e sound from rear DT car 'A4' door. ~~~~~ 3534 Pax feedback to staff(NEW) whistling sound from train. Staff(DBG) heard faint air seepage sound from 3533 'A4' door. CE: 3533 check no whistling sound on A4 door. OE depot check.  3533 A4 door checked/found no air seepage but found RHS door roller damaged. Replaced door roller & cleaned J-rail. Function check all doors - OK.  Alan/Sugu/Lee PT 44735