Super Ikonta 531/16 missing film plate

[nonuniform]

Just bought off eBay a Super Ikonta 531/16, which turns out to be missing the pressure plate on the inside of the camera back.

I've already contacted the seller about returning the camera, but in the meantime, the camera is very clean, I'm wondering whether I can find the part that I need.

Any thoughts? I could negotiate for a partial refund, keep the camera and fix it.