I have the VTBP-201. It is the older 1.5u model, that I picked up from a fellow TB'er. It sounds great! The volume pot has seemed to gone ou though. From the Low position if you start to turn it up, it will switch on, but stay constant. If you crank it up, it stays at the same level. Its either on or off. Would this be the volume pot is bad, or would it be something more like the tube??? Any Ideas? Thanks!