Trouble fixing handle/closing mechanism on double glazed window

Hi all,
The handle on one of my windows connects internally to a kind of cog, which when turned, causes a bar running along the side of the window to move up and down. The bar has two "pins" for the sake of a better word, which lock into brackets on the window frame. Recently, the "cog" bit broke so the handle turns and does nothing useful. I've dismantled the mechanisn (fortunately, it broke in the open position!), but for the life of me don't know how I'll find a replacement for the cog like bit which is inside a bar like structure which is in turn held in place by the riveted pins. The windows were fitted around 10-15 years ago and I've no idea who supplied them, however I suspect this mechanism is relatively common. (can't find any makers details on any windows I've examined).
Can anyone point me towards where I might be able to buy some new ratchet/cog/slidey bits to fit in the window and allow me to close it again.
many thanks
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