Fix the water entry first. The crown is the sloped concrete cap on top of the stack, and its hairline cracks are invisible from the ground. Tuckpointing beneath a leaking chimney crown, missing cap, or failed flashing simply re-wets the new mortar, and the repointing fails within a few seasons.
Most chimney leak repair calls in Toledo trace back to one of three points: a cracked crown, a missing or damaged chimney cap, or step flashing that has pulled away at the roofline. Water passing through any of them saturates the masonry below, then freezes and expands through Northwest Ohio's repeated winter swings. White powder on the brick face, called efflorescence, is mineral salt carried out by that moving water and confirms the chimney is taking it in. On framed, sided chimney chases the equivalent failure is the metal chase cover: builder-grade galvanized covers rust through and drain rust-colored streaks down the siding, which homeowners often mistake for a roof leak. A stainless replacement cover with a sealed storm collar corrects it with no brickwork at all.