Is the red steel blower housing flexible, or rigid? If firm hand-pressure will deflect it so it doesn't touch the float bowl, I doubt that it matters. On the other hand if it is rigid, it is pushing the carburetor out of position. That would potentially cause insufficient clamping pressure on the insulator between the carburetor and cylinder head. A leak there will cause lean mixture, which is what you seem to have.
Has the previous tenant removed the carburetor, and either accidentally or deliberately omitted the insulator, or one or both of its gaskets? Or removed the cooling cowl and reinstalled it incorrectly? That could cause approximately what you've got.
