Ouch, that's pretty bad. From reading elsewhere on this forum I'm led to believe that the problem might be related to small weights beneath the keys. They're supposed to be glued in place, but unfortunately many found out that the sticky stuff isn't very strong, hence those weights are prone to fall or break off in time, sooner rather than later.
Some folks here apparently have tried a DIY solution by disassembling the unit and apply some super glue. All very fine, but while that may fix one thing, it will surely break any claims to warranty. What if a different problem occurs?
I'm curious what kind of reply you'll get. It's really pretty dumb that an otherwise very nice product is marred by something as trivial as glue!