I have a px-150 for around 3-4 years now, today i noticed that one of the notes is significantly louder than the rest. its louder in a weird way, it produces a sharper sound than the other keys, a sound i cannot reproduce by hitting harder on another key. the difference remains on different voices, vibraphone for example. i suspect one of the sensors went bad when i bumped into it early today but can't really tell. did anyone experience any issue of that sort? and do you think i can try and solve it by opening up the piano and having a closer look? (total amateur when it comes to fixing stuff). also is there a "hardwhere" manual for the piano i can have a look at if i am to open it up?