A lot of old cheap electrical products use wax to insulate and glue the windings of motors & transformers together. If the motor overheated it would melt. Maybe the heat would change the nature of the substance so it remained liquid. It would be a design feature to prevent the wax gumming up the motor and waggle mechanism. Which if that didn't happen would cause a much more catastrophic failure.

Just guessing but with experience of electricals & design.