Not a Fender amp guru myself, but I'm confused as to why the master volume is evil... unless you're wanting that Fender-clean-shimmer... clueless here lol.
I'll try to answer this as best as I can. Blackface fenders and silverfaces have different
circuitry. Since fenders are known for clean sound, during the cbs-era they added
master volumes to kinda enhance the clean souns but instead it just makes the amp
sound sort of thin and distorted at higher volumes. That's why alot of people have their silverface amps blackfaced because a blackface can give you an overdriven tone at higher volumes.