Those are called t-nuts. It is common for these to break during removal on System 11 games like Diner because they were threadlocked (like a blue glue) into place during manufacture to prevent them coming loose during play. I hate that this was done and always have a few break on me. Gottlieb Sys 3 games have this issue too.

Relatively easy to replace if you have them on hand.

https://www.pinballlife.com/6-32-tee-nuts.html

The common sizes are 6-32, 8-32, 10-32

RussM

You can either:

1. Raise the drop target into the Up position and jam a piece of folded cardboard under the reset plate to hold it up while you install new decals from the top side

2. Disconnect the connectors (2 I think, one to power the reset coil and one for the switches) and unscrew the bracket and pull the whole assembly out.

RussM