Kurzweil makes a nice instrument. Unfortunately, their action manufacturer, Fatar, has a hit-or-miss record.
There are many different models of Fatar actions that Kurzweil uses, some better than others. I'm not sure what action the piano you're referring to uses, but here are some things to take in to consideration:
The TP/10 action found in the K2500X, PC88 and possibly others used weights made of lead. These lead weights were housed in a plastic cradle. The plastic was brittle and the lead expanded and contracted depending on temperature. Combine this with repetitive up and down movement, and the weights would often break free of their housings and begin rattling around inside the keyboard. There was, and still isn't a good fix for this, aside from buying a whole new action. Actions are not affordable. This seemed to affect some batches more than others. I have seen 15-year-old PC88's still in perfect working condition and I have seen others with a completely unusable action. Some of this probably depended on how they were played and handled.
Kurzweil began using steel instead of lead sometime around 1999 when the K2600 came out. My '99 K2600 is still working perfectly with zero problems. What is the age of the piano you are looking at? If it is older than 1999, I would pass (especially considering what all has improved in terms of sound quality).
So there are potential reliability issues. Now, let's talk parts availability.
Fatar has a bad habit of introducing new models of actions and abandoning the old versions, thus cutting off parts supply. I ordered some spare keys off a parts keyboard on eBay for my K2600 just in case, because I found that I can no longer buy replacement keys for my K2600. Mind you, production on this model stopped only a few years ago. Same is also true with the K2500 and PC88.
If this keyboard is already well-used and still has no issues, most likely you will be okay. Fatar's actions generally broke down within the first few years of ownership. There is another thread here about key noise and possible flattening of felts, but all things considered, this is an easy (and expected) problem with any keyboard.
EDIT: For some reason, I was under the impression that you were looking at a used board. Since you have this new model with (hopefully) the TP/50 action, you should be covered for quite some time. Fatar has also seemed to really improve their action found in the PC3 (which uses the TP/50). People seem happy with them, and no failures that I know of have been reported. Hopefully they provide parts longer in to the future. I have a feeling that they will -- generally, when they develop a new action, they will use it in many different keyboards for years and years before moving on to something else.
Edited by LesCharles73 (01/29/11 11:49 AM)
Les C Deal