Do you have a keybed with weights that are glued to the keys? If you have a Keylab with blobs or thin threads of glue underneath, then it looks like you need a keybed replacement, just like the case was with my Keylab25. After a few months I got a floating key that would click when pressed. The click was caused by a disattached weight. I returned the Keylab to the shop, from where it would be sent to the repair service elsewhere. But instead of a quick fix for the key in question it was decided to send the Keylab to France, where a different kind of keybed was embedded.
It makes sense, because after a simple fix of that one key, another problem key could follow shortly. From my observation I can say that the replacement keybed is more solid and not as fragile as the blobs-of-glue one. I wish I got it like that when buying it, so I wouldn't have to wait more than six weeks for the case to be solved. But okay, I have a warranty and time flies anyway.
I suggest you return your instrument and do like I did. I strongly advise you to NOT open your Keylab and go DIY, like others did in order to save time. It will invalidate your warranty and you will be stuck with the less-than-solid type. This is what I'm saying, but eventually the choice is yours.