I don't know if it's common or I'm just "lucky". My seat was shaky when I flipped it up and I noticed the pivot pin had worked its way partially out. I removed it to check and the end was drilled for a cotter pin. I put on a thin layer of grease to ease installation and put it back into its proper place. I used a hitch pin to secure it. Now I'm wondering if I should have used a washer as well. I'll have to have another look at it.