Fixing window handle - asy job? (pics included)

Hi all

I need to replace the handle on this window. It's a bit wobbly and I can feel that it's about to come off in my hand.

When showing the OH, we realised that in fact the window is not locking. The circular mechanism in picture 2 that should move up when twisting the handle isn't moving at all.

I understand that replacing the handle itself isn't a big deal as I watched my mother do it before :pac: but, if the circular bit isn't moving upwards, is this a bigger problem?

I'll probably just replace handle anyway and we will see, but until I can get my hands on one, does anyone know for sure?

Thanks in advance

IMAGES: https://imgur.com/gallery/DOWXWK5