I have the same problem. I was going to just replace the whole portlight with a new one but after reading this thread I realized if you have the original engineering drawing of the handle you could probably print it using a 3D printer.
I just sent Lewmar a request for an engineering drawing of the handle. I suggested they publish drawings for all the parts
they no longer stock.
If I get the drawing I'll either share it here if allowed or share instructions on how to obtain the drawing.
If I don't get the drawing I might ask my friends son who just completed his high school
CAD class to try to draw one up. If it works I'll gladly share it here.