Blackberry

We are still working on this unique Singer Industrial Machine and today we got the belt from sew classic and after my husband got it on it seems like the treadle will only go backwards. So he got down to take a look and sure enough there is a ball in the belt pathway. It seems the ball goes into the dip in the wheel when the machine is treadling backwards but it completely stops when you try to treadle forward like the regular treadle machines. Does anyone know if this machine only treadles backward. He has to tighten the belt a little more before I can tell if the backwards treadling will turn the wheel. Just wondering if anyone of this board has any knowledge about this machine. I know the cabinet would have been much nicer if the original owner had not painted it white but that is the way it came to us and I don't believe we could have stripped all of the white paint off so we just left it.