I'm trying to install a set of Posies super slide springs on my 49ish chassis and can't seem to get any of them to fit into the pockets. The frame has been freshly powder coated but I have cleaned the surfaces to bare metal and even ground on the sides of the springs but cannot get the (non-shackle) end into the pocket. They seem to get tight after going about halfway in as if the ears on the pocket are tapered. Am I doing something wrong? Should I just grind more off the spring eye?