You don’t seal through the carbon, you seal each page in the carbon set. Otherwise the seal would be a big blob from the paper creasing and sliding around as the pressure to cram the paper through into the holes.
As a notary of government forms, I never sealed through the carbon. You typed the carbon and then sealed each paper in the set.
I thought about that but you wouldn’t send the carbon set out as the original and no reason to stamp a carbon set that was to be simply filed.
Its just a light typewriter. I never changed my ribbon until it about like the type in the document.
John