"O" is the match relay currieddog paulace based on the schematic you shared. There should be a switch tied to the 5th and 4th trough switches, by a blue/white wire. On the opposite side of the 5th trough switch should be a white wire. So you need to trace the blue/white wire from the 4th trough switch to the next switch in line. The on ball release switch would have a blue/white wire going to one leaf and then (Guessing, as your photo does not show it, but other similar era gottlieb schematics do) the other leaf will be tied to a red/white wire.
https://www.ipdb.org/showpic.pl?id=2208&picno=65339&zoom=1
is a prototype game of slick chick but you can see the two switches for 4th and 5th ball trough switch and the blue/white and white wires. I would trace from there to determine where the blue/white to red/white switch is. You can also find the 4th skill hole switch in the same photo(and in your game) it should have a blue/white wire attached to that switch, that wire should trace to the same on ball release switch, or a jumper that goes to said switch.

Hope this makes some sense...

Manually pull in the coil. Make sure that switch is opening properly.