From the top of Big Bald going down the back side of the mountain, there's camp site almost immediately to the left when you enter the forest. The path to the cave will be on the right a few more steps ahead. Keep you eyes open for yellow markers. There will be one point in the trail where the path looks to go straight so look for a yellow marker on the right and another if you turn right at that point. Not too far ahead look for a double marker which indicates a sharp turn ahead left.
From this point, the path starts to get steep so slow down and look for yellow markers which will be often, not always obvious, but they're there. In time the path will be improved.
Special thanks to everyone's friend off the mountain, Darcy, for showing us the location.
GPS 35.991023, -82.496395