Why does my hotbin get cold?

[Lady Macbeth]

Hello!
so I’m new to hotbin composting but I was doing really well. I have called mine ‘Clementine’ (I name most inanimate objects) and she was raging up to 60 degrees ☺️ She was producing the liquid gold juice, and still is, but despite my following the rules, she is down to just under 40 degrees 😳
can anyone help please?
🙏🏻

[HotBinDjinn]

Likely an issue with airflow caused by the mixture becoming too wet or alternatively too much brown material and the green material being all but used up. Hard to tell without seeing it. Mix in some more woodchip and cardboard if it's looking too wet. Take some of the wetter stuff out of the bottom, remix it, and put it in the top. Add some green stuff if its looking too dry. Also check the air valve at the top is open. Mine gets closed regulary by the neighbour's cat standing on it as it uses the hotbin as a step up to get over the wall.

[Lady Macbeth]

Many thanks! She’s up to 40-60 degrees now!