Hi, my name is Anthony King. I've been the owner of my 1974 Super Bass 100W now for 28 years..bought it in 1988. I found this forum looking for answers as mine is being worked on. It was modded pretty good when I bought it and played many a punk rock shows with it this ways. In 2001, I had it brought back to stock a la Billy Zoom from the band X. He does great amp work. He also put in a wattage attenuator in the back to bring the volume down. I then had it brought to '69 Plexi specs from another friend out here in Tx..Cody Pappas. It sounded really great at this point. I took it upon myself to re-tube and bias and set the bias too high so it was super clean without much compression. Anyways long story short, Cody says there's some weird stuff going on with the polarity switch and I recently bought a THD power soak so I am in the process of having that looked at as well as taking the wattage attenuator out and just using the Power soak. I want to keep the '69 plexi mod in there but bring everything else back to original. I hope to learn a lot from this forum and possibly get some ideas to keep this Marshall alive and well! I believe this amplifier to be the best sounding amp when it's working right..I love the sound of it and am trying to get it back to sounding great and maybe even better.