Hi Geoff and thanks again for the answers. I managed to get the screw it and although I couldn't get the exact same size, I managed to use "rawly lug heavyweight plasterboard fixing" screws. The size is M 3x50 mm once anyone needs to replace. The threadingdoesn'tgo all the way to the top but works fine.

It was pilot error I think. All screws were super hard to adjust but now age replacing the broken one are easy to turn.

1st repair and I'm gaining confidence.

Thanks again for the answer Geoff

Gav