Here you go.

https://landroverforums.com/forum/di...or-plug-41294/

And the brass plug is a lot easier to get in/out for inspection for calcium, filling with coolant and DISTILLED water (goes good mith many distilled spirits as well), and some have suggested attaching a pressure guage for testing. The plastic one is one step up from a crush washer....

Help!
 

Attempted to use the knife idea, but the knife only scraped off black plastic and I could not turn it. I began chipping away and got a great deal of it out, but as I did this a big piece went down and into the radiator. I cannot see it, nor could I fish it out with anything.

Any suggestions for removing it? Should I crank it up and wait for the coolant/plastic piece to come out? Would it come through the drain hose? Any ideas?

You need to drain the system now, the rest of the plug should come out.