Ted,
I just finished up Railfan & Railroad's list of operable North American steam for 2007. I called the museum a few weeks ago and was told that they plan to have locomotives 4, 7, and 8 in service this year. They are working to have 7 and 8 ready for the National Narrow Gauge Convention. For the past few seasons they have operated with just one locomotive, Monson 4.
Jeff Terry