formula pre schematic

[harry manback]

hey guys. i'm a noob here, but i've got a formula pre that has been serving me quite well since i got it. the other day, though, it just stopped putting out sound, and i'm not sure why. i checked the tubes and jacks, but everything looks good. is there a schematic floating around that i can look at and maybe diagnose my problem. i'm also gonna do the mod to it afterwords, so that's kind of my secondary motive in getting it.

thanks for your help guys.

jeff.