I have measure the voltages on Q7, Q8 and Q9 on the left (faulty) channel- Q7 b 10v, e 10v, q8 e 8.4v b9.3v. This suggests that Q8 is functioning (b-e=0.9v), however on the good right channel Q7b 0.2v and e 1.5v and Q8 b 0.6v and e -0.5v.
Q9 on the left b 6v and e 8.7v, where as on the right...