The assy with plunger is A-11388-2
The plate itself is 01-10380
This part was broken on my T2 and has been broken on a few other games with that drop target assy I've owned, restored or serviced over the years.
Bay Area Amusements, Marco Specialties, and a few others have these in the US, I think someone on your side of the planet will have them as well :)
They are used on a lot of games, so you might buy 2 and have a spare. Especially if you're going to pay shipping from the US!