(Can't find the forum relating to PF components. Since it is about the Carousel, I guess it could be placed in the Town forum)
Anyway, for the 10257 Carousel, Lego recommends the M-Motor.
My M-Motor from July 2017 has already become weaker and worn out! I guess it is not robust enough. Has anyone tried the L-Motor with the set?
The video shows the trouble I have.