Marvin awning window, circa 1960

I'd like to replace the crank mechanism unde the handle in which the gears are stripped. Not sure if I need just the crank mechanism or the arms connected to the crank. The sash bar is 23" long and the two arms look to be about 9" long each. The handle case is 51/4" wide (left to right), about 1" tall (top to bottom), and about 11/4" deep (front to back)