One of my tilt turn windows has started to stick. I suspect the
problem is at the hinge mechanism.

The handle will no longer go to the fully upright "12 o'clock"
position.

I've tried a little oil and grease without success.

If I was to dismantle it, could anyone suggest how easy or difficult
it might be to reassemble and replace it?

I'm reluctant to get the window fully replaced for what is probably
just something in the mechanism that could probably be repaired.

Can anyone point to any resources that might illustrate how the
mechanism works?

Thanks for any help.