It's the coils that squeal, they're the only part that has anything that can move mechanically.

In the olden days of the late 80s when I had a high school job at weekends repairing TVs there was a particular family of Bang and Olufsen TVs where you had to desolder a choke in the power supply, smear it all full of some sort of resinous goo (they recommended a particular epoxy; I found that Isopon car body filler was the gold standard, setting into slightly flexible polyester that didn't fall off or crack).

Within the repair industry it had been nicknamed "Beobuzz", after all the other "Beo<something>" products.