I have the same problem with a friends watch. Appears the ends are rolled or threaded.
I tried this, all the pins are fixed though, the Seiko one is spring loaded.Search for " tube friction pin " on you know where,I think that's what you might be looking for as I had the same issues ....
Ha! I did the same to a Fossil watch once, then later bought an exact model on evilbay for $8.00, cannibalized the pin, and sold the donor for $11.00 on the same site with 'pin missing'I don't know whether new correct replacements are available but I repaired a broken clasp using a paper clip of the correct size.
Once cut to length I peened the ends over and it worked fine![]()