The customer had purchased this vintage Bassman 70 with plans to clean it up, and while it initially worked fine, once he got it home it would only produce noise. The source of the madness was a missing nut and washer on the bias control pot. Without the nut the pot was no longer making contact to the chassis/ground. One little bit of hardware had thrown off the whole amp. I locked down the pot and biased the new power tubes. I also gave the front panel pots a good cleaning. Some people don't care for Fender's ultra-linear amps, but this one had a nice solid clean tone that was exactly what the customer was looking for.