Hi everybody, I have the same problem, the lower C!!! Need to clean the black rubber? look the picture please http://s11.postimg.org/sn6fnhzmb/20151030_214639.jpg http://s11.postimg.org/sn6fnhzmb/20151030_21... View on s11.postimg.org Preview by Yahoo try to slide it and clean but didn' work :(