When I add a quarter to the game the replay wheel increases two steps, but no knocker. When a high score thresh hold is reached, the wheel increases one step, but no knocker.
Oddly, if I manually push the Replay Step-Up EOS closed, or manually work the step-up solenoid, the knocker fires. If I watch while someone drops a quarter in, the step-up solenoid fires and the EOS closes solidly but no knocker.
It seems that the red path on the schematic is good when I manually close the EOS switch, but NOT good when the machine closes the EOS switch at quarter drop or high score thresh hold. (I'm not the best at schematics, so please let me know if my red line is wrong or I'm missing some other factor.)