I doubt Q106, Z101 or Q102 will have any bearing on bias. Can I assume you are measuring bias across R133 and 145? The 10 ohm resistors?
You might experiment with R112 moving up from 680 ohms to closer to 1K. That may give you your adjustment back.
Other than the bias transistor itself which may be suffering from low gain, the transistors that have the most profound effect on bias are Q101, Q107, Q108, Q117. If the base-emitter drop of these devices has dropped over the years, you will have a hard time getting the bias down.