This is weird. I tipped my 210XLT sideways to put it in a car ... and heard/felt this "clop" inside. Later on I picked it up and started "shaking" - not violently, but just sort of "curling" it up and down a bit ... sure enough, it sounds like something is either loose or rattling around in there. It sounds pretty substantial - not like a little loose wire banging the back plate, but more like something knocking a bigger surface that resonates. I share a space with a couple of other guys, one of whom also has a 210XLT - so I picked his up and gave it a similar shake. No rattle. The cab sounds fine when I play through it ... although I have noticed what I thought was clipping when I really crank up. I thought the problem was that my GK800RB was running out of juice and I was getting amp clipping - but maybe there's something dodgy with the cab itself? Hmm. Any suggestions? It doesn't seem like the drivers are moving when I do the "shake." But maybe the cone is flexing a little, and what I'm hearing is the drivers reaching the end of the "resting" excursion range? Thanks!