Feedback Problems Krank Rev 50

[BrianBosboom]

Hey guys,

My Krank is making a weird, shaky feedback sound when I turn the volume past 3 or 4, and sometimes when I change channels.

Here is a link to a video I made, it will show you what I'm talking about:
http://www.youtube.com/watch?v=guQT6rEaBkg

Anyone know what's wrong with it?

Thanks!