If your Wii is hacked, professionals will NOT repair it at all.
Not true... there is one possible way to do it, but if you do it, note that you won't be able to play backup's from the disc drive anymore. They replace it with the newer drive that makes it not possible to read dvd's.
What you have to do is brick your wii to the point where it has the black screen that comes up upon booting the wii. If you wanna know if you have it right, look up savemiifrii and try to bring up the recovery menu. If you can't bring it up then nintendo won't be able to detect your hacks.
I did this about a year ago though... so I don't know the status on if they can detect it now, so don't take my word for it. You could just start playing your games from a usb loader.