I have the opportunity to buy a Hegner polymax three scroll saw made in 1986. I will attempt to show a picture of it ,which in my opinion shows the machine in great condition except for that the large plastic pulley has disintegrated. does anyone know how expensive this might be to replace? I am not sure the size of this machine yet but when I looked up the model it seems like they are supposed to be 20 inches and that this is the professional/industrial model.