I own a Kalamazoo 2 but am a total idiot when it comes to mods. I did, however, find quite a bit of info on the Kalamazoo Amp Field Guide dealing with tone control upgrades, adding cathode resisitor bypass caps and the like. Once you get rid of the original plug and reduce the hum, these are sweet little amps. That CTS speaker, however, has got to go.
"I don't play a lot of fancy guitar. I don't want to play it. The kind of guitar I want to play is mean, mean licks." John Lee Hooker