zooming in on the pics it seems someone has "pointed" the stack and
flaunching around pots with silicone?....

Was that done after the problem 1st manifested or is that a previous
bodge?

I see what you're saying. They have been back once to try and
resolve, but I'm not sure exactly what they did. I think I need to
get up there and take a look myself as camera pics (camera stuck to
broom handle poked out of windows!) aren't ideal.