hiss on xenyx 2442 fx

[selmax]

i need some help i have a xenyx 2442fx which is make a hiss sound on channel 6,8 9/10 and 11/12 this is when the mic trim is at 3/4 turn clockwise and the fader is at 0. No mic is at the inputs also the headphones hiss with or without a signal.
i replace the headphone ic's 1 and 2. i have also replaced the caps in the power supply. the rest of the channels are working without the hiss.

[Jazz P Bass]

On any of the troublesome channels, do any of the tone controls (tone circuit) change the hiss?
If they do, try changing the first opamp (first after the input jack)

[selmax]

i have the channels fixed. the hiss is on the headphone with all channels muted main and group switch in the off position on the channel the source for the headphone is main or any of the group i get hiss but no hiss on the main output or the group output lines.

[Jazz P Bass]

[QUOTE=selmax;314634]i have the channels fixed.QUOTE]

What did you do to fix the channels?
(I have attached the headphone circuit for those that want to play along at home)

[selmax]

i changed the c25, c41, c42, c51 and c52 and the hiss on the channels stopped.