Casement window arm rusted off

Hi there! We can definitely help with this. It looks to me like you need a new casement window hinge. I recommend our 36-004-10; this set contains a pair of stainless steel replacement hinges for windows just like yours. I feel confident that you can use them to repair your window as long as you replace both the top and bottom at the same time. 

The 36-004-10 hinges are also stainless steel, so hopefully corrosion won't be a problem like this in the future. 

You should also watch the video below for insight on how this hardware works.

Sure thing! If you needed anything else, you know where to find me.