Hi! Bought a Siggery 7-string a few month back on ebay and though it's quite a nice guitar the truss rod gets loose if you're not tightening it enough and you can hear the thing raddle inside the neck. It might not sound like a problem but the tone gets weird when the truss rod is loose. When i tighten it there's too much of a back bow causing some buzz on the lower frets. I could probably get thicker strings to get more tension and less back bow, but is there any other solution?