Koshering a milk frother / immersion blender

I have a glass milk frother that I only use with milk but the part that froths is metal and plastic. Can I use it? Is there a way to kosher or no need?

Also my immersion blender stick is metal but the top attached is plastic. I guess it’s the same issue. Is koshering possible?

Thank you for all your help!

You can kasher it by frothing or heating water instead of milk. However it is not necessary to kasher it as per your description.