This casement window is 25 - 30 years old, no longer closes.

Can you please tell me the correct replacement part for this window. I'm not sure how you measure the arm.
I'd like a left and a right side part.
Long arm says Entry Guard Truth, number 30472RH on the back.
Short arm says number 30842R and 20810 on different parts of the front
Base has a 6 and 40471 on the top, with a 91 and a 43 on either end.
Thanks, Joe V