Lowen Replacements options , current crank or upgrade slider ?

Thanks for posting. You're showing two different window operators here--you are showing a lever operator for an awning window, as well as the worm gear and handle for a casement window operator. In both cases, I will need to see the entire mechanism, including the gear box and arm(s), from a bird's eye perspective, with either the operator removed from the window or at least with the window open. Such a clear view will narrow down your options. Many thanks. 

Thanks for these photos. This appears to be a different operator style compared to what you show above. There are a few different versions that might match this one but it's difficult to tell without seeing the complete mechanism out of the window. Many important details are missing.

For now, my top recommendations would be the 39-015, 39-083, and 39-140. You can start with these to see how well they match the original. If these don't match, however, or if you aren't sure, then I will reiterate that the best way to identify these is to remove the operator from the window in its entirety and show me one clear photo of the whole thing in one shot. That's how these are routinely identified, so anything else will lead to uncertain results.