Morning from the UK,
I have a PAM438 Ceramic from InTime purchased about 2 years agp, however one of the pins in the clasp has broken/fallen out and now the strap will not lock. Attached is a picture of the empty pin hole
I doubt you can buy a part that small. If you can measure the remaining pin, maybe have one made for the other side. Your worst case scenario would be to buy a whole bracelet.