Not really sure how he ended up with a Japanese model, I asked mum and she has no idea.
I’ve discovered the part number for the crystal is 290T04ANS. Cousins don’t seem to have it in stock, but I’ll register with them and ask the question. Not sure if they could source the pins too.
I think it will only need the end pins nearest the lugs, the rest aren’t too bad. Would any watchmaker keep generic pins that would do, or are they likely to be special items? Need to take a closer look at it, I fear the holes in the lugs could actually be the problem rather than the pins themselves.
Potential for the crystal, though they are trade only:
https://gleave.london/glass-seiko-290t04ans/