I don't know specifically.
I've seen the glass removed then holes drilled inside frame to get at the mechanism in windows to trigger and open it.
Some how you need to trigger the multi point locking..
Maybe get a firm in to sort. You will need a new casement lock which is another problem when you do open
Has the spindle worn or the hole it goes through in the latch. If it's the former then obviously use a different spindle. If it's the latter then try turning it with a flat bladed screwdriver that you can jam in the hole.
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