My method of adding machines to buze 0.5.9 or any buzz, is starting from zero, if I need anything I will put it in the generators or effects folder. Usually I add stuff people recommend here in the forums. Or I hear and like something from a developer, so add a few more stuff from same developer. Instability issues are related to machines I thought, generally.
There is also buzztrax (before buzztard), but ubuntu software-center of 14.04 LTS has only version 0.6 there, latest is 0.10.x, tried installing it myself, lots of troubles or dependencies, you have to install them first successfully, not easy crossing this trouble forest of errors, compilation errors due to missing libraries.
My latest horror story was trying to install MidiJoystick*, then I had to install first a huge development environment, took long time, laptop almost could not do anything else, then again errors, just trying to get a small MidiJoystick program work in linux.
*
https://github.com/osune/MidiJoystick