Rockhopper said:Its likely that the backplate has corroded away.
B21 said:There are no parking brake shoes on an E89..the rear disc brake pads are moved by an electro mechanical jack screw to push the pads against the disc for parking..its very unlikely that the pad material has seperated from its back plate..simple procedure is to replace both pads..suggest you get an appropriate Indy who knows E89s to do this job..