I want to replace the valve seals on a 216 motor. I have a valve spring tool and it compresses the springs but the keeper at the top won't come out. I've tried this on several springs and none of them will come out. What am I missing or doing wrong? Also, what's the consensus on the type of seals to use, umbrella or O ring? I'm not doing a rebuild at this time, just replacing some leaking seals and gaskets.