I have a 2007 Rubicon that the oil pump chain has come off. I have gotten to the chain and am trying to replace the old one with a new one. I can't get the oil pump drive gear off. Is there something special that has to happen? It is just a 10mm bolt but all it does is spin also there is what seems to be a lot of play in the gear assembly itself. i.e. it moves in and out a little and has side to side slack is this normal? Help needed please.