My Square-1 was like that. The wear from months of looseness made it perfect
Take off the other center cap; you'll find a trapezoidal prism platic piece with a hole. Put glue in there, then drill in the screw while holding on to it. Keep the spring slightly compressed until the glue is dry. Only strong glue will work well, so make sure that you don't think you'll take it apart again unless you're desparate. That Square-1 will never
come apart again by accident.