Counterbound T410 reported T211 left side headlight not working. TC of T211 checked and confirmed le ft side headlight not working. Train was reformed with a sch edule withdrawal returning back to BSD. ~~~~~ 3709 Counterbound T410 reported T211 left side headlight not working. TC of T211 checked and confirmed left side headlight not working.    CE unable to board  Replaced blown 3709 B/S headlight. Function checked ok. Done by: Henry 45299