I just picked up Rumble 410 cab and today I noticed a certain rattle coming out of it when I play through it. I turned the volume up and down and played different notes but I keep hearing it. Like something came loose inside. I moved it from the bed room into another room thinking it was a piece of furniture or something but the more I examined it, the more I believe its the cabinet. Or a speaker. Each speaker works. I put my ear to each one and I watched them move also. But it could be internal..It could be the tweeter. Should I open it up and investigate? I was thinking of returning her for a refund. It was the floor model and I know they don't have any more left. What should I do?