In the Facebook group, Joey Hayes reports that work is being done on the G-Force ride today. He submitted this photo:
According to a member of park management, it sounds like this is just routine maintenance that needs to be done every eight years or so.
G-Force was added to the park in 1997. It was originally located outside where the Scrambler currently sits. After the side of Main Street burnt down in 2010, the park rebuilt it and moved the G-Force indoors. You can read more about it on the Adventurelandians Wiki: