Headphone repair company? (Electrets)

Can anyone recommend a good company that can repair electret headphones?

Specifically I have a pair of Toshiba HR-811 Electret headphones that are playing intermittently and I suspect the inline transformer has something to do with it so its bit beyond my skill level to repair. Given the fact that they're electret cans I'm hoping there someone reputable that can take them on.
 
I thought you would get "instant " advice on headfi but none so far----.

Hifi engine has no downloads on it.

Its possible that there is dust on the stators but its dicey trying to clean electrets as they have a special coating to help hold the charge . Its also possible that the transformer is not connecting properly but that could be in the cup or plug .

If it plays okay at times then its more likely a bad connection.