Check that T7 and T8 and their diodes are ok. Check all 4 of the 0R33 5W resistors.
Power up on the bulb with no load connected.
Measure DC volts at e,b,c, of T4, T6, T9, T12.
Power up on the bulb with no load connected.
Measure DC volts at e,b,c, of T4, T6, T9, T12.