Snap: 2521 B1 door, loud noise heard fro ~~~~~ 2521-Bogie 1 physically checked-Ok. Checked G/Way #1 End-C/o G/Way footplate due to noise abnormality-Security & Function check-Ok. Depot movement-Fault still persist. Suspect 2521 #1 End coupler fault. Notification raised for 2521 #1 Coupler c/o.    Low K.C / Hafiz R. / Hariharan.  11.09.2023.    2521 #1 G/Way Footplate. Noti to RSW-2522784. 2521 #1 Coupler C/o. Noti to RSW- 2522783.