The next tests should be of the transistors on the pc board. You need to test all 7 of them. Start with the driver transistors Q3, Q4, and Q5. Then test the protection circuit transistors Q6 and Q7, and finally the two input transistors Q1 and Q2.
There are 4 PNP transistors and 3 NPN transistors. The difference will mean that you will get low readings from base to emitter and base to collector with the red meter lead connected to the base or with the black lead connected to the base of the transistors. Typically the NPN's Q3, Q4 and Q6 will read low with the red lead on the base and the PNP's will read low with the black lead on the base.
There will be a little problem with testing the two protection transistors as there are low value resistors that connect the base and the emitter. As long as there are no zero readings, you can probably assume that the transistors are okay. If there is any real doubt, then remove them from the board to test them.
Finally test all 5 diodes in the circuit. With your meter, they should read just like a transistor junction, low reading in one direction and open in the other.
Tell me what transistors and diodes you have replaced, and what you used as replacements for them.