Does the leaf blower work anywhere else?

Yes, even on other plugs on that circuit

Have you pulled the outlet out to visually verify that it's wired correctly? if not, be sure to turn off the circuit to be safe.
Otherwise try replacing the outlet to be sure and safe.

Probably a worn outlet or a loose connection. Try bending the blades of the plug outwards just a tiny bit. If that doesn't work you'll have to do what Wizard suggested, keep in mind a loose connection (like a blown out backstab) could exist at any one of the outlets upstream of the ones you are having issues with, even one that works OK. Vacuum cleaners are the best tool I know of for exposing weak backstabs.