distributor

I have pulled the distributor on my 225 ,and it seems to have two O rings ,one in the grooved slot and a large one at the bottom of the hold down plate ,I don't think the large one should be there ,as upon replacement the dizzy seems to be moving ,and I don't want to damage the nylon gear as the dizzy seems to be new,ive only just bought the car ,and I don't know too much about slantys