Tandberg Huldra 8 , hybridreceiver , made 1965

Hallo! Trying to repair this receivers both 10W output-transistoramps don´t work ! A pair of PNP , AD150 in PP are fed by +33VDC. The lower AD150 has its collector tied to ground . The same problem for both channels is that only about 1,5 VDC could be measured in "the midlle". ( there shall be
+15VDC . The driverpair is AC127/ AC 128 . A fifth transistor,
a silicon SE6001 is the voltagestage . All transistor are OK ,
so the diodeand two trimpots . It seems to me when I measure voltages that the upper two devices , one AD150 and its driver, AC127 are "choked" and/or two of the three lower transistors conducting too much . ( the voltagetr. is choked too ). As a tubeampguy I must admit that I´m not so familiar with these transistoramps . Any comment or advice
would be very much appreciated . Regards Stewen