Last night during rehearsal I noticed that when I hit certain notes my cabinet would give off a pretty bad buzz. Sounds like something could be loose. When I lowered the volume the buzz/rattle goes away. Any ideas or suggestions what to check for? For what it's worth I was playing a pbass through a Streamliner 900. The notes that created the most buzz were a C on the E, and D, D#, E on the A.