Thanks! I couldn't think of any other way to clamp down the wood pieces and make it easily accessible to adjust the bias. Later if I get ambitious or bored I might vent the bottom and move the bias trimmers to the bottom of the PCB so I wouldn't have to remove the top. I think if I were to do it again I would put a small panel meter someplace and put the test points and trimmers on the back panel so I'd never have to open it up.