entire apparatus comes out of the crank holder

Hello, thank you for posting,

Unfortunately since the spline is stripped out of the operator base, the full mechanism will need to be replaced. To further review, we will need to see the window open where we can view the operator arm(s). From there we can confirm the best fit for your window. 

With the window unlocked, you should be able to gently push open the sash to expose the arm(s). Thank you!