One of the keys on my CP4 sound a little "hot" compared to the others. It's the "A" above middle "C". I've been able to control it using EQ but I saw a video on You Tube where someone took the key section out of their digital piano and simply cleaned the printed circuit board. Could this be some dust or dirt and simply needs to be cleaned, or should I take it to a music store for repair? Appreciate any suggestions.