Distributor seems loose..

I noticed today that my distributor seems kinda wobbly.. hold down strap is tight. I removed to unit to check the bottom slot screw and that was tight also. The small o ring is in place. There is also a large o ring at the base.. Seems like the big o ring is making it wobble. I search here for some answers but they where mixed. Some guys say that they never knew there was a big o ring.. Really just trying to figure out if it should be tighter. Thanks