TC reported of metal sound heard from undercarriage of train. TC checked at WDL SB headwall and conf irmed no abnormalities. ~~~~~ TC reported of metal sound heard from un     Check and observed #3649 B/S cab door having gap to train body.Readjust cab door gap having few mm improvement.U/F check no observed any abnormalities.To be further monitoring. Done by Koh. 9/11/21