How do they do the welcome show when they train is being refurbished?
They do the same welcome show with some differences. I have seen both version with and without train. Personally, I love the train one the best.
If the train is not operational:
The Mayor or Fire Chief comes out and starts the show. The Trolly singers then come out and sign "Good Morning To You". Then if no train, Mickey and the gang with the Family of the day come out and walk across the tracks to the railing and open the park. A CM sets up a walkway that spans the exposed tracks like a gangway prior to show start.
If the train is operational:
The Mayor or Fire Chief comes out and starts the show. The Trolly singers then come out and sign "Good Morning To You". Then "Casey Jr." song starts and steam train pulls into the station with Mickey and the gang along with the Family of the day. The exit the train towards the railing and open the park with small fireworks.
Either way it an awesome way to start your day. In my opinion it is the best welcome show Disney does that I know of.
Each of the other parks do a rope drop ceremony as well but not as grand in my view. In some of the parks, DL included they let you walk down to the hub even before the park opens to where their rope drop ceremony starts.
MK is unique in that you cannot even enter the tunnels until the show is over. They keep everyone corralled in the entrance plaza between the turnstiles and the tunnels. Unless of course you have an early morning breakfast reservation in the park. They will let those guests in for that.
I think I am going to try a breakfast reservation in the park in January just so I can experience all the guests rushing into the park. Plus cool pics of the park mostly empty.
I have also been there on at least one occasion where they did not do any welcome show at park open. That was a bummer.