I also had to send mine to Nintendo because 17 days after purchase I discovered it wouldn't read discs properly. I hadn't noticed before because I only had Wii Sports and I hadn't taken it out of the Wii.
I sent it on Monday and I am now waiting impatiently for them to send it back mended, or a replacement.
I'll tell you what the service is like (I live in Spain) and I have written down the serial number to know if I get a replacement or the same one.!