The mesh is riveted to the outside of the dish. IDK. Might not be a Unimesh.If it is a Unimesh, the screen fits into a slot on both sides of the rib. The problem is getting to the slot at the outer edge of the dish. I have two Unimesh dishes, and they have a lip covering the end of the mesh on the outer edge of the dish. It prevents you from getting to the slots so you can slide new screen into the channel.
As far as I can tell, there's no way to remove the outer edge of the frame to expose the end of the slots. I have a small battery operated reciprocating saw that uses a hack saw blade. I have been kicking around the idea of cutting the lip off the end of the frame to expose the slots. I's not sure why they did it that way because there are two sets of screws that hold the mesh in place.