Breakthrough!

The 8 V rail was not making it through the transistor stage I was testing.

That gives me a much more useful place to focus the troubleshooting.

It does not, by itself, prove that the transistor itself is the only faulty component.

The surrounding bias, control and power circuitry still need to be considered.

But compared with “somewhere inside the Aiwa there is no power”, this is substantial progress.

One fault narrowed down.

Many, many boards to go.