Mighty Jet 326 noise

[Mystichrome]

Does anyone know why all of a sudden I'm getting bubbling noises from my mighty jet 326? It was pretty quiet, and I didn't really do much but a small water change? Its noticeably loud all of a sudden? I've tried everything from taking it out, checking the impeller. It sounds like there are literal bubbles in the return chamber but I don't see anything there. The level of the water in the chamber is just below the baffle. I have an Intank media basket, which I'm not sure is contributing to it or not? 

 

If I turn off and on the pump it goes quiet for a few minutes and then the noise comes back?

[j.falk]

Did you figure out what the issue was?  I installed a MightyJet 326 yesterday and it was silent upon start up...this morning it has gotten a lot louder.  I can clearly hear a humming / vibrating sound that I don't recall hearing at all yesterday.