Class 375 Awful Sound

[Doomotron]

While waiting for my train to Broadstairs an empty Class 375 drove through empty with the seventh or eighth coach making a horrible clanging sound. The sound was incredibly loud, I could hear it for up to a mile beyond my station. I'd assume it was a wheel flat but I've never seen one that loud. It sounded like the whole train was falling apart.

This is it on Real Time Trains. Does anybody know exactly what was wrong with this train?

 

[CarrotPie]

While waiting for my train to Broadstairs an empty Class 375 drove through empty with the seventh or eighth coach making a horrible clanging sound. The sound was incredibly loud, I could hear it for up to a mile beyond my station. I'd assume it was a wheel flat but I've never seen one that loud. It sounded like the whole train was falling apart.
View attachment 121591
This is it on Real Time Trains. Does anybody know exactly what was wrong with this train?

Was forming this to Dover. Cancelled +44 at Canterbury East due to a brake problem.

 

[Future]

It was a VSTP movement as 2U01 had been caped at Canterbury East due to 'a problem with the brakes', at which point it was running 44L. The delay can be seen in the ECS that formed 2U01 as well, so I'd assume some fault with the air brakes somewhere, although that delay reason is very inspecific