Hi Courtney, I’ve just been down and taken some plastics off to have a look. TBH I hadn’t remembered this from when I cleaned my playfield a few weeks ago so I had to take a closer look.
It is not completely consistent but in most cases the taller posts go under the holes in the plastics and a threaded bolt comes up through them and the hole to be fixed with a plastic nut.
The exception to this seems to be on the plastics just above the pop bumpers where none of mine seem to be tall posts, even those under the holes and fixed with a nut.
The pictures may help but to take the plastics one at a time:
Both posts under the holes in the slingshot plastics are tall.
Top right plastic…only one post just under the word WHEN is tall
Middle right plastic, numbering the posts from top to bottom, numbers 1,3 and 6 are tall.
Middle left plastic, from the top, number 1 and 4 are tall.
Top left, I think the posts under the holes in the plastics are tall (forgot to number these).
Of course no guarantee these are correct all I can say is they work and it’s how the machine came to me!
If you want me to check anything else please let me know. Pictures follow. Best wishes, John