> the exhaust appears very old and not well maintained

Sounds like the exhaust has been there a while. Now - was it malfunctioning when they looked at the apartment/moved in and this is a recent change I think is a valid question.

> a situation where a nuisance existed before you moved in significantly limits the legal options available to address the nuisance.

I rented an apartment once, off a local veterinarian, right next to his practice. While I lived there he had built a crematory right outside my back window, the place was typical Pittsburgh 1st floor in the front, walk out basement in the back so my apartment was basically at smoke-stack level.

My lease was up and I ended up moving out for other reasons, but man I would have been pissed if I was stuck in a lease and had to look at that thing running.