failure senssor of mixtrak pro

Hello friends! guys I'm with a doubt! I have a MIXTRACK PRO but she from when I bought is defective which sometimes when I play in the dishes senssibilidade system does not work touch on the plate and the band keeps rolling. I noticed that when I disconnect the RCA cable from the desk or P2 if any it works normal. I even thought it was problem of ma changed the RCA cables and also the P2 but the evil contact continues. anyone there has any idea how I can solve this problem? from already thank you very much for the crowd's attention thanks!