<html> Kevin, I'll have to second what Allan says.  What you described is almost certainly string vibration, not plate.  A plate ring will have a distinct pitch to it (or group of pitches), and will not ring sympathetically like you described. 2 things come to mind that could be the cause: - Leaking bass dampers.  Even though they follow the strings, they could be letting tone through.  This may not be a bad thing, actually, as people sometimes get used to it and don't like it if the dampers are too effective. - Open strings below the bridge or above the pressure bar.  I haven't seen this model recently enough to know if the waste ends of the strings are felted off - check that. Don Mannino RPT </html>