schematic needed for Jen phase shifter

[EDADmartin]

Hello,
          I bought a Jen kps-900 phase shifter a few years ago to fix,and never did.Now I need a schematic for reference or if there is a qualified tech that would fix it fairly that would be cool too. I get intermintent sound or just pops when the foot switch is depressed.I can very faintly hear a pulse sort of a tic,tic very low.Any Ideas  ?