Home DIY

over the course of a about a month, it's generated a little poo (for want of better word) that sits on top of where the crack is - a sludgy brown semi-solid perhaps the size of a thumbnail.

@user69121 - thanks! i didn't even realise earlier that this bit was a joint/each vertical section (do they have a name?) was an individual connected part - assumed the whole thing was one big hunk of metal..! in many ways, good to know as that hopefully means the metal itself isn't pitted and full of holes (touch wood)