As the ball kicks over, it rolls over the Trough switch which should activate the Add Player Unit relay (P)

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pasted_image (resized).png

It looks like the part with the pins and springs is upside down. the arm with a single pin/spring should be on top and the arm with two pins/spings should be on the bottom.

solar ciy (resized).jpg

Can you talk a picture of the opposite side. (both positions as above)

The bonus unit contact, that should close at initial position, looks like always closed and might need some adjustment. But first make sure the switch stack screws are tight.

Was the unit recently cleaned?

I am wondering if the spring is too tight.
Can you unwind in one turn? (You may have to move the switch stack out of the way)

Or there is is stop on the underside of the gear and the gear need to be re-positioned so the stop is on the other side.

you're missing the white tubular switch lifter on the switch blade and your ratchet is installed incorrectly.

the length of the switch lifter is critical for reliable operation ... too short and you won't be able to adjust the switches correctly (don't ask how I know that).

you should be able to hold in the reset coil plunger, spin the ratchet counter-clockwise and when you let go, it whizzes back to the stop bracket argosysk mentioned and stops. The pin on the ratchet only pushes the switch blades when the unit is stepped up to the top step (15 steps counter-clockwise).

below is blibb's pic from another solar city topic showing the ratchet in the unit reset position.

if ya get a chance, can you post a picture of the score motor? Either the timing diagram on the schematic for switch 4D is wrong or I have an odd score motor configuration on a solar city.
solar city bonus ratchet (resized).jpg

Congratulations Alberto! You're one step closer. The slow count is exactly the issue I was dealing with, so follow baldtwit 's advice for me, and you should end up with a machine gun stepper as well. The game is so much better with fast, accurate, scoring.

for slow bonus count:

1] the G relay needs to stay powered the entire time the bonus unit is stepping. If it is powering/unpowering, you'll miss pulses and the stepping will be irregular.

2] score motor 4D provides one pulse per score motor cycle (120 degrees). Score motor 4A provides 5 more during the cycle. If 4A not working, you get a regular but slow bonus step-up.

3] K relay switch with GR-YEL and BLK+RED wires needs to be closed unless you are scoring double bonus. K relay should only power when scoring double bonus.

the thunk as those 120V coils operate is pretty noticeable. It's better when the game is closed up, but if it's the only thing in the room making noise, you'll hear it every time.

if the mechanism is rattling tho, you may have broken torsion springs on the bar the plungers operate.