My pads are broken and I don't know why

SachaLRF

Hello, I have a mikro MK3 and some of the pads don't respond as they use to do and do not work even when I changed the sensivity in the settings, I never made it fall down or set down on it or haven't spilled anything on it or even being to strong with the using, it juste started to do this like that. Maybe the place I live is a bit cold and humid, but I guess it is not that much. I called everybody in and out of Paris and nobody can help me... What can I do ?