Ygriega

I have a similar problem on my casio gp 510, which I bought a little over 2 weeks ago. The piece that runs the width of the piano, sitting above the keys vibrates, especially with a strong key press and on chords. It happens intermittently on mine, and occurs when the volume is up, or off, or the piano is powered off. When playing forte chords with the volume up, it vibrates even more and almost sounds like a blown speaker. I tested as kate g did, by gently pressing on the piece that is causing the problem, and it squeaks very lightly. If I press on in gently while I play, it won't resonate/vibrate. For the cost of such an instrument, nothing should be wrong with it. I contacted casio support by phone yesterday and they told me to contact the dealer where I purchased the instrument. Hopefully the issue can be fixed. I love the action on this piano and the tones, especially the Hamburg and Vienna grand. It's a shame to have something so small ruin what is otherwise a great instrument.