Seat Foam Removal Q's

I'm replacing the upholstery on my seats (73-74 A-body buckets) and I've run into a small problem. The seat foam is in great shape, but the frame needs some welding repair. As the foam wraps right around the frame, I am having trouble telling how to remove the foam (it seems continuous, like it was molded onto the frame) so that I can re-use it. Any tips?

Thanks!

The foam has it's own metal grid...Look carefully from the front seating area where the upholstery listing wires attach...The foam is usually attached in the same channel as the listing wires are...Once you've removed the listing wire go back and look in the same spot and you'll see another hogring holding the foam metal grid to the seat frame...It's tough but the trick is to cut the hogring with as little damage to the foam as possible...
The foam's been on there for a long time and is shaped to the frame nicely...Some foam has cloth attached to it and is in turn fastened to the frame around the perimeter either by the seat frame metal "hooks" sticking up or hogringed holes...
Take your time and you'll see them...