Try going in and change your touch sensitive up and down and then to what you normally keep it. As you do this, see how the change sounds when playing a note. See if it just needed refreshing.

Awhile back, going out of my KN7000 the volume dropped on the left side. It would be OK for a minute and then drop in volume almost completely. All I had to do was work up and down a few times, the main volume and no more problem.

Mark