Hello,
It seems like you are referring to the operator that opens and closes the window. If so, we would need to see your operator fully removed from the window to get a clear view of the arms that move the sash since the base is a common style used by many variations of casement operators. Thank you!
Unforutnately, your new photos do not give us any new information since the base is the only part shown. We'd still need to see the arms that connect the base to the window sash in order to narrow down your replacement options.
Thanks for getting back to us. I would recommend starting by looking at our 39-022. This has an 11" long arm and rear-mounted screw holes.
With that being said, it seems like your operator arm may be closer to 9-1/2". If so, a better choice would be our 39-139. The only issue is that this has face-mounted screws rather than rear-mounted like your original assembly. There is a workaround for this though. You would just need to use our 33-205 threaded insert by pressing it in with a vise. That will allow you to mount it the same way. Take a look and see if one of these replacement options could work for your repair.