The Bb2 key on my Yamaha keyboard is faulty and makes it very difficult to play.When pressed it sounds at full volume regardless of how hard it is struck. I have cleaned the key contacts using Isopropyl Alcohol on a cotton bud to no avail. (I also have a Roland synth which sometimes does the same thing and this method cures it). Is there a component in the touch sensitive circuit that needs replacing ?. Any advice would be welcome. There are no service facilities handy to where I live. Regards..................Pedals