I bought some of the Seimitsu PS-14-K clear snap ins recently from arcadeshop.de.
It looks like the K's are out of stock but they do have the Seimitsu PS-14-KN's (they have a nut rather than being snap in).
I dont think they have nut type in when I ordered mine, I wish I had got them instead.
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Heres] the link to the PS-14-KN's.