Audio Amplifier Repair Explanation
I would start by making sure the thing is biased correctly.  Look at the voltage at both bases of the differential pair.  They should both be zero.  If that is the case, then I'd look for the signal on R44.  You should see a nice amplified SIN there.  Next I would check for the points that say 1.2V.  The bottom one on TR16 should be -1.2 not 1.2.  It's hard to say more without component values.  what is the value of R44?  

Check to  make sure substitute transistors have the same pin outs as the originals.