I have played the Privia 400 many times at my store and have demonstrated and sold many of them. The tones are found by simply selecting a catagory using the buttons on the front panel and then using the data wheel to select the different tones within the catagory selected. I find the tones mostly pleasing although not the best. I don't know how to tell you if your keyboard is malfunctioning or if you just don't like Casio's voices. Comparing these sounds to other keyboards, I would give them about a 5 or 6 in a 1-10 rating. For it's price, I think you get more then you pay for.
George Kaye
Kaye's Music Scene
Reseda, California