I just picked up a Kodak Six-Sixteen folder and the only problem is that the shutter blades are stuck open.Could this be a case of old lubricant dried up or could a more serious problem lurking beneath the surface (so to speak).
It could be anything, but it is most likely either rust or oil on the blades or in the works. Try a quick and dirty bath in naptha after removing the elements. If this loosens it up, you have your answer. If you really like and want to keep using the shutter, a more professional CLA would then be in order.