[dberman51]

You'll find that the secondary will be sensitive to polarity, and unfortunately the markings on the replacement transformer won't help you determine which terminal to use for the ground side and which for the high side. One way will give you negative feedback and work, the other will give you positive feedback and bad oscillation. I would first set up the voltage divider for a tiny amount of feedback (maybe 5%) and then test to see which connection reduces the volume of the amplifier.

-David