Sewing in reverse?

My Toyota 2700 is sewing in reverse, the button seems to do nothing. I have taken the side off to look at the reverse lever and when it is pushed down, it does not seem to alter anything inside. It does have an arm that looks as though it should push a bar down at the back of thespecial button hole adjustment, but this is already in the down position on a spring. I can see some screws, do they need adjusting to make this in an upwards position?