new strap pins for Seiko frankenmonster

[Tiggsy]

Picked up a mint, unused, Seiko five on eBay the other day - in adjusting the strap I have lost a couple of the "shoulders" that slide onto the end of the pins in the bracelet to hold them in place. Where on earth can I get replacements? Or can I replace with a more common split pin affair?

Otherwise I'm looking at sticking it on a NATO!