From Loonipedia

All I know of Animaniacs is "Toy Shop Terror," in which the entire episode is based around a complete and brilliant arrangement of "Powerhouse." I communicated with Stone before he scored the episode, and he had to fight the suits at WB to allow him to use the full version. WB owned the publishing on PH until 1965, at which point the rights reverted to Scott, who sold them to Music Sales Corp. WB saw the writing on the wall. They knew they were going to lose Scott's catalog as each title reached 28 years after original copyright. That's why they stopped using Scott tunes in 1962. They didn't want to have to license Scott tunes from another company. They gave Greg Ford a hard time when he used some Scott in the late 1980s. They insisted that Hal Willner remove references to Scott in the liner notes for the Carl Stalling Project (one made it thru the final edit), even though there are 12 Scott quotes on the CD. So my hat's off to Stone. He deserves the kudos. You should watch that episode.