Earthway Seeder fix
 

whenever I plant peas, the seeds work their way behind the white seed plate. It doesn't seem to happen with any other seed. I think as the seed plate turns the seeds get caught along the downward turning section. A line of hot glue on the backing along this side of the plate should keep the seeds away from the edge.

Earthway Seeders have a hard time with corn too. Nice of you to post your quick fix.

It is untested but it should work. There is site that shows how to use a large PVC end cap to stiffen the seed plates, but it looks like it might be hard to use. I might hot glue a stiffening ring to the pea plate.