Agitator

The agitator is inclined to exaggerate trivial matters.

Tom needs to call someone to repair the agitator on the washing machine.

Tom needs to call someone to repair the agitator in the washing machine.

The secret of the agitator is to make himself as stupid as his audience; thereby they believe they are as clever as he is.

Near-synonyms: instigator; see also Thesaurus:troublemaker

In addition, they kept a watch on political agitators and foreigners arriving and departing at the port.

I’m only aware of one anti-ICE raid incident in California over the summer in which a single agitator pointed a pistol at federal agents, and that person is apparently still at large.