You may be SOL. The photo in your link shows blades that look different than those for other OXO peelers. You might try calling Fantes in Philly or the oldest indie kitchen shops you can find–the idea being places that sold your peeler, who might have new old stock.
You find me a replacement natural bristle head for my Lamsonsharp BBQ brush, I’ll track down your blades.
Edit: The Amazon ad for the OXO Pro Y peeler at the OXO store shows a photo of what looks to be the same tricorner blade cassette.
