can't tell from the picture angle what wires are connected, but you probably aren't missing switch blades.

there's four sets of switches on the cam 4. The top set is SPDT, so it has a moving middle blade with blades above and below it. The below blade should have wire 95-50 on it.

the wires attached to lugs on the top of the stack are for configuring the coin behavior of the machine. MA75 has these options:

1] one coin = one cycle of the machine - the bottom blade of the SPDT should be jumpered to wire 18-11
2] one coin = one cycle + 4 credits added. Bottom blade jumpered to 15-5
3] 2 coins needed to produce either of the above. wire 25-30 on one of the top lugs jumpered to either 18-11 or 15-5

when you have credits on the replay register, the coin switch shouldn't do anything.

the SPDT top blade has wire 14-5 on it. It's job is to trip the tilt trip relay if the coin switch is closed when the timer cams lift up the cam 4 switch stack. It's there to help prevent people from fishing a coin on a string to toggle the coin switch. If it annoys you, you can disable the tilt by misadjusting the top blade permanently open.

there's no guarantee an operator jumpered things the way bally intended. As long as closing the coin switch causes either the start relay or multi-play relay to power, that's the end goal for options [1] and [2] above. Option [3] the coin switch just powers the alternator relay which in turn steps the alternator unit once.

flipper games usually had all this stuff configured with plugs. For whatever reason, the bingos almost always required soldering wires to set the coin behavior the way the operator wanted it.