My charger began making a humming sound while plugged in but with no battery charging. Is it going bad?

I'm not sure about the humming. But if you need to get a replacement. We have the BC-U1 compatible charger in a much affordable price.

Sony Compatible BG-U1 Charger for BP-U65/BP-U95 | L.A. Color Shop (http://lacolorshop.com/products/item.asp?id=u1)