crank arm piece of Andersen window

Thanks for writing in. I am afraid these old Andersen operators and their associated parts like the track aren't made anymore. Depending on your old operator's appearance, you may be able to use our Andersen 39-094 or 39-095 as replacements; but I believe this is going to take some adaptation of the window to work. 

Another possibility is using the 39-504 track with the 39-365 or 39-366. The main problem here is the track. Our 39-504 track need to be mounted to the bottom of the sash. Now, yours is mounted at the bottom, but it sticks out from the sash. I can't be sure, but maybe you can use your existing track with the 39-365 and 39-366 operator as long as the end bearing fits. I believe either option will take some adapting to fit no matter what.