Never replaced a pad, but I was a TC on one that carried six nukes near the Fulda gap just after Kennedy was shot! We were ready to heat it up if the Russians moved.
October 1973: Egypt attacked across the Suez Canal; Israel counterattacks and crosses the canal into Egypt. Soviet Union announces intent to send paratroops to help Egypt. Tricky Dick Nixon raises DEFCON status.
At this time I was no longer the mess officer in a Pershing 1A missile battery but had moved to battalion HQ - Asst S3 training officer. I was also an EAO - emergency action officer - and when the duty NCO in the operations center got an alert standby, he rang a buzzer to get an "A" team member in to decode the message. I hot footed over to the ops center and got there first. The alert message for once was real, and not an exercise message. With the message decoded and authenticated, I hot footed it this time over to the battalion conference room where a commanders' meeting was going on. I burst into the room without knocking and announced that we were at a certain readiness state that, among other things, authorized load out and dispersal of our missiles WITH warheads.
The alert message part that authorized us to deploy was rescinded some hours later, but one of our sister battalions that had its storage sites closer to its barracks was already rolling. At the time of the alert we were way too busy to consider the implications of what we were doing. We had so many practice alerts that everything went like clock work. In fact, it was really impressive to see how fast and efficiently everybody worked when they knew this was for REAL and not another drill.