When I was putting on the valve cover after a valve adjustment, I was tighting the crown nuts on the spark plug cover and I heard a snap. Apparently, the bolt that you would tighten the crown nut and the nut underneath it broke right above the black metal seal thing. I used a torque wrench set at the right setting so I know I didn’t over do it. Is there anything to do to replace that snapped bolt? Luckily, the black seal still stays put without the nut but still, but makes me feel a bit uneasy. Any advice?