No experience here, so don't take any of my advice or listen to me.
It sounds like you're having some success which is good. I know I've read on here before that people will often soak overnight or maybe even a few days. Sure you will want to monitor them often though. I would probably lean more towards that than trying to pry anything as that sounds problematic. I wonder if it's an option and you have enough space to cut or tear the pages and just soak the card with page segment.
Either way, keep us posted and let's see them! I'm sure someone with lots of experience will chime in with sound advice.