Ibanez TS-10 help! [SOLVED]

[InTelejens]

I have an Ibanez TS-10 Tubescreamer which powers up and works in bypass mode only.
When I engage the effect, there is no sound.
I've checked the input and output jacks and the circuitboard for any obvious issues but didn't see anything out of place.
I've signal traced the circuit and found that there may be a problem with Q8, the switching transistor.
I swapped out Q8 with another 2SK118 and the problem still persists.
I've checked the gate diode and resistors and 0.047uf cap but they all are in spec.
Can anyone shed some light on this matter?

[Dirk_Hendrik]

What's the voltage of your virtual ground? (Hit: Measure on the cold lug of the volumecontrol)

[InTelejens]

Thanks Dirk!
I measured the voltages on the JRC4558 op-amp and this is what I found:
Pin1: 9.5V Pin8: 8.5V
Pin2: 8.5V Pin7: 8.5V
Pin3: 8.5V Pin6: 8.5V
Pin4: 8.5V Pin5: 0V

It's pretty clear that the op-amp is bad.
I installed a socket and a new 4558 op-amp and it's working again!

[Dirk_Hendrik]

Cool!!