Found the culprit,
When I took the covers off, I could see what appears to be s0me sort of plug on the end of the pipe I circled in the picture above.mit seemed to have popped out... There doesn't seem to be any clips to hold it in.
So I just taped it up until I can get a bit of day light to take the bracket off to get a better look.
Seems to be fine now now:)