There's a buzz at my first A string only when played in open position. #After searching the archives I believe it's a nut slot that's a tad too deep. #The second A string(the 4th string on the instrument) is just fine. Not being knowledgeable, #I'm not confident playing around with filing etc. Is the best fix to raise the height a few thousandths with some method of filling the slot? And if so, then how?