Need fuzz circuit help

[ringmos]

So I have this fuzz circuit from a book of electronics projects and I'd like to understand it better and play with the sound a bit.



I have it on my breadboard and it works, mostly. The questions I have are:

Which are the transistor biasing resistors and what values can I use to change the sound?

Also, the 1M pot is supposed to adjust the amount of fuzz, but doesn't seem to do anything. Any ideas?

Thanks for the help.

Marc