SOS need help finding replacement cranks

Hi there! 
Thank you in advance for your assistance. I forwarn that all terminology I use was learned in the past hour so please bear with me!
I have 4 left hinge windows needing replacement crank assemblies. I cannot for the life of me find a manufacturer in the window or cranks. 
 
On the crank arm (I think that's the name of the V shaped piece) there is what appears to be serial number 08030501. What I think are the 8 and 3 are faint and could be either 3/8.
Each piece has a 4 digit number stamped on it - the main white part is 2023, crank arm is 3019, and the last piece that connects to the window is 3108.
On the last piece that attached to the window is a little metal plate. I'm guessing that this plate is riveted on and if I had to reuse it I'll have to break the rivet and use a new one. 
Any and all information as to how to replace these mechanisms would be greatly appreciated. It seems wasteful to replace a whole window when all I need is new crank assemblies. 
 
If you need any additional information or pictures of the crank as installed please let me know. 
 
Thank you!!!