I recently had my second set of cores recast. In switching out the hardware I cannot for the life of me get the retaining screw to grab and screw in to the new core. I have tried solvents, wd40, a wire brush, an awl and curses, but to no avail. I’ve tried all 4 ends of the 2 cores, and none of the screws want to go in. Is there an ever-so-slightly-smaller version of this screw? Please help!!