Well,
The Hacker Sovereign RP18 I was repairing for a friend now works, all 4 AF114's responded well to the treatment. Once I had replaced the diodes in the ratio detector, it sounded even better, one had gone leaky, and I couldn't balance it.
This technique certainly seems to work, for how long we can't be sure.
Even better was the fact that I performed the act with the transistors in circuit. They are a
to remove in the RP18.
Pete