In message , Graham.
writes

OK, if it was mine I might try to damp the vibration with copious
amounts of Araldite, but when giving advice to others I like to
promote best practice.

Aerosol varnish reaches the parts others don't. This has stopped
numerous transformers buzzing over the years, normally cheap and nasty
ones found in the more "cost effective" types of equipment.
--
Bill