If you can visibly see the windings that are loose, you can possibly fix it. It's a bit abnormal, but throw down some high heat resistant glue on it.
Some people have used nail polish or Epoxy, though both can soften when warm. Don't use consumer glue like Elmers, hot glue gun sticks, super glue or anything like that. You want something that hardens but doesn't necessarily require high strength, just density/no softening.
If you look at most yokes, there is a huge blob of black or reddish brown epoxy (like what are used for IC blobs) over most of the yoke windings. This is done by the manufacturer to prevent your problem from occuring over time.