just got a Lightning clone in a trade. It sounds real good but has a problem when guitar volume is over 7........it starts this buzz that sounds like a bad speaker. Already tried a extension can with 2x12's and still does the same thing. I also replaced all tubes with proven tubes and inspected everthing fo make sure nothing was loose, burnt or obviously broken. I am able to get a reasonable amount of volume, but as soon as I turn up the guitar the problem comes back............I suspect the retaining springs on the el84's.......they are awful close to the tubes and to my thinking my be touching the tubes once the get cooking and vibrating a little..... anyone ever had a problem similiar to this?