You can sometimes remove wrinkles from a strop by filling a thick glass jar or bottle with hot water and rolling it over the crease, with the strop on a flat surface of course.

The Norton 4/8K is probably fine, but lapping will make certain it is flat and clean. A DMT D8C diamond stone is good for the job, but do the lapping under running water. Round off the edges and corners of the Norton once you are done.

If you never plan to restore old razors you can go for the DMT D8X instead of the D8C.