Tom and Jerry - Piano Tooners (1932)(avi){Zzzzz}

Tom and Jerry (the human versions, not the cat and mouse) work as piano tuners. After seeing them at work and several creative ways of tuning a piano (such as removing the offending key and cutting the key itself to a shorter length), the two attend an opera singers performance. The singer passes out when the piano plays a wrong note, and Tom and Jerry are pressed into service to re-tune the piano. After pulling the offending key from the keyboard like a bad tooth, the two give the opera audience a jazz piano performance, with the now recovered opera singer joining in.

http://www.imdb.com/title/tt0151965/