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As you already measured the voltage at the R26/R27 point as 0.2-0.3V then this should be the voltage you see at the base of both TR6 and TR7, the base current should be so small you should see virtually no voltage drop through the trasnformer windings. If it is not then you either have transistors the wrong way round or there is a problem with the driver transformer or the transistors are broken.
The voltage you measured at the potential divider giving the base voltage was correct.
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I agree with what you say Jeff. With TR6 and 7 out of circuit, but with T1 secondary in circuit the base bias voltage is OK. This points to R26 and R27 being of the correct value or failing that in the correct ratio.
With TR6 and 7 in circuit the base voltage rises, so additional current must be being pulled through R26 increasing the voltage drop across it. This current can only be flowing into the base of TR6 and/or TR7. This is assuming of course that it is actually the bases which are connected to T1 secondary.
Are far as I can see though even if TR6 and 7 collector and emitter were connected directly across the battery it still wouldn't result in the base curent increasing enough to increase the base voltage.