A clock case can be physically level and the clock will not run because it is not in beat.

Putting a clock in beat means setting the clock up to give an even tick and tock sound, which produces the most efficient running condition for the clock.

To determine if the clock is in beat, start it and listen to the tick & tock as the case is slowly raised on one side and then the other; a wedge or shim placed under the side of the case works well. When the tick & tock is even or sounds about the same, the clock is in beat and will run the best.

If your clock is in beat and the case is not level, a part on the clock called the "crutch" needs to be adjusted to fix this condition, and adjusting the crutch should be left to an experienced clock person.