I have a 1966 Fender Twin and a 1966 Pro Reverb and would like to change tubes and experiment a little with different ones. Taking it to the tech everytime is expensive and a pain in the butt for what seems to take him less than 5 minutes to do. Is biasing this type of amp very hard? Is there anywhere that has simple easy to follow instructions so I can do it myself? What do I need and how much money do I need to spend to get the right tools for the job? Help and advice appreciated. Thanks Guys. I love this forum.