Is there a walkthrough available somewhere?
I've got 19 items in my inventory but can't find a cleaner or a way to open the door downstairs.
Viewing post in Date of the Tentacle comments
Have a look at the books in the living room to get somethng that can work like a cleaner.
If you mean the door on the left next to the stairs ... use a hook that you find somewhere to unlock it.
I hope it helps. For the first half there is a walkthrough on YouTube further down in the comments.
Part two is here: