Kurzweil K2500X key replacement help

Hi, I just got my hands on a Kurzweil K2500X but the keys are in pretty bad shape and I’d like to replace them. They’re yellowed and brittle, a few have been broken.

Can I just replace the plastic keys? Is there anything else I’d have to change out as well? If I can just replace the plastic keys, is there somewhere I can get all 88? I can only find single keys or an octaves worth.

I’m rather new to piano, and I haven’t been able to find much about changing the keys. Thanks!