I have the SD spb-4 installed in my partcaster bass. Yesterday I was playing it for a bit, put it down to eat dinner, and came back only to find out that something was wrong. The pole for the D string stopped working, for lack of better term. The only reason there's sound for that string is from the other poles. I know there are hundreds of forums for this, but I don't know where to start. I've never seen this before. Can anyone link some discussions or better yet any explanations? Cheers.