Stuck saracen lock on uPVC window

[Decker]

We have a window that is stuck closed. It appears (based on the window next to it) to have a Saracen deadlock gearbox with rods that extend directly into the frame (when closed) as opposed to having a roller.

The handle will turn and one side of the window will slightly move (1-2mm) when trying to open but the other side will not move at all.

I am assuming the gearbox has malfunctioned/broken and thus the rod will not retract, hence this side of the window not moving.

My question is how can I remove the gearbox and rods to replace when I cannot get the window open?

Many thanks in advance

 

[crank39]

Remove the glass to allow the frame to flex, slide in a very rigid wide scraper between the frame and opener and lever the opener over the frame keep

 

[Decker]

Thanks crank39, makes sense but a bit beyond my skill set and tools. Will get a professional in.