Outside of the room that houses the pipe organ, there is some information about the restoration. Here is the text as it reads on the sign. (Please note the hyperlinks in the text)
By 1800 there were five pipe organs in the Moravian towns in Wachovia. Two of them were in Salem, and both were built by David Tannenberg (1728-1804), a Moravian from Lititz, Pennsylvania, who is considered to be the premiere 18th century American organ builder. Of the fifty organs he built for Protestant and Catholic churches between 1765 and 1804, fewer than ten survive.
Tannenberg's first organ for Salem was a one-manual organ built in 1798 for the Saal (meeting room) in the Gensein Haus (the Congregation House). This organ is not on exhibit in the Single Brothers' House. The second organ, finished in 1800, was a much larger one for the new church, now known as Home Maravian Church. This organ is the largest surviving instrument from Tanneberg's shop. It has two manual keyboards, a pedal keyboard, 644 pipes, and eleven manual and two pedal stops.
The organ is on loan to Old Salem from Home Moravian Church, where it was used in the church from 1800 to 1910. Because of subsequent changes to the church's interior, the organ cannot be returned to its original location. In order for the organ to be restored, Old Salem constructed this hall for the organ. Through a meticulous process Taylor & Boody Organbuilders of Staunton, Virginia, restored the organ to its original playable splendor.
While researching this topic, I also found this remarkable video on YouTube.
Also, here is a link to a nice Our State Magazine story.