A few hours above where I live is a huge Amish area and there is a supplier who has more parts for more meat grinders than I have ever seen.
This outfit will ship world wide too.
When I was there they had a room full of kero lamp chimneys of every imaginable size.
It was like stepping back 150 years in time.
You may contact them with info about your grinder and if they can provide it they sure will ship it.
Another thought is to visit a machine shop toward the end of the week like on a Friday when it is slow. Show them the blade and ask if they would know how to sharpen it or suggest for you to sharpen it. You may be able to place it on a fine
piece of sand paper on a very flat surface and just move it around in circles. Do both sides. They may have a suggestion for a method to do it and the grade of
sand paper or whatever.