Orvis is suppose to be very good and gentle for washing things like this, I believe. Those green centers in the first photo look like they are coming apart? They just look strange in the photo so I am not sure if that is what is happening. Anyway, if the blocks don't flatten out when you hand soak/wash them, your idea about "halving" or "quartering" them sounds like a good solution. You might just want to make a wall hanging or perhaps table top quilt where it won't get any traffic to harm them if they are too delicate. I hope others chime in with suggestions and ideas to save these old blocks. Good luck!