Look at bottom right of the schematic. See the 1000 point relay and the five circles below it (2D scm through 7a scm). Those are switches on the score motor. Look at the score motor diagram in the upper left (two Zs). See how the 2 row has 5 in a row, and the 3-7 each only have 1 per row.
When C and D relays are both off, the 2D switch pulses 5x for the single bonus, when C and D are on, the connection for 2D is cut and instead 3D, 4A, 6A, and 7A let pulses through. Note switch stack 5 is missing, that's why you get the ... between the double dings. So one of those four switches isn't making contact and needs to be cleaned. (the letter is which switch in the stack it is, with A at the bottom)