audio research 100.2 trouble

[maxpou]

Hi Guys,
i have a ARC 100.2 in trouble here. The muting circuit is always on and the led flash. I have 0V in gate of Q47, 0.06V in base of Q41,42, -7V in gate of Q44 and 0.6v in pin2 of U3. I d'ont understand the utility of the circuit with the optocoupler RY3. Someone can help me?

I found this schema on the net

Maxpou

 

[maxpou]

Hi guys,
someone can tell me a good replacement for Q44 in the muting circuit?

thank you!Maxpou