The lug broke off the switch, you will need to solder in a new switch.

Pretty common problem. You'll need to replace the switch since one of the leads broke off. I have tried putting hot glue around the base of the leads to help support them, with mixed success. I usually grab a couple of these switches whenever doing a pinball life order.

https://www.pinballlife.com/vuk-vertical-up-kicker-switch.html?Category_Code=

Like others have said you need to replace the switch. Get one where you can swap over the actuator so you don't need to worry about that. Although mine is on location (5 years), I've swapped in probably 3 switches with broken solder lugs like yours and had to resolder broken wires at least 12 times. Not joking.

Take a picture of what lugs the wires get soldered to. Small Philips head screwdriver to remove the 2 small screws. Don't drop or lose the screws. Hopefully you got the type of switch with the removable actuator. That way you can just swap it over to the new switch.

Did you get this fixed? I just replaced the same switch on my machine two days ago. Very easy.

Exactly the same green wire cut at the middle lead as northothewall.
I have order 2 spare switch from Stern Europe parts.
What nutdriver size and screwdriver are needed ?