A support assembly includes a support rotatable along a first surface with respect to a support rail, a repetition lever rotatable on the support, and a jack rotatable on the support and disposed to at least partially overlaps the repetition lever. The repetition lever includes a first contact portion which makes contact with a regulating portion which regulates rotation, the jack includes a second contact portion which makes contact with the regulating portion which regulates rotation, and the repetition lever and the jack are provided so that the first contact portion and the second contact portion overlap each other.