Stripped crank handle

Our house was built in '91 & contains awning windows. One of the handles fell off in my hand when I tried to open the window. The handyman said the internal workings were stripped & I needed to order a new part. We live in a marine layer & most of the metal arms are covered with white (salt? calcium?) & rust, but aren't broken. I finally found a window that was protected from the salt air & found a stamp of a house & "Truth" etched in the arm. So I think I'm in the right place. I'm not sure if I need to replace the entire unit or just the part with the crank. That part is 5 inches across. Any help would be appreciated. Thank you.