who has CDJ400s

Oh great DJTT gurus....
I'm posting this for a friend, he just bought a pair of CDJ400s used and is having an issue. One works perfect, but the other doesn't want to eject cds correctly. When he puts in a CD, the CDJ reads it fine, but when he ejects, it starts to eject, and then pulls the disk back inside and starts trying to load it again. Has anyone else had a problem like this? Dude is so stoked to have his new players, but isn't too happy that only one works properly.
Come on guys who want a CDJ forum here, show us why we should have one! :)

disc loading sensors buggered,
minor fix, not expensive