I agree with Leon, except for the comment about reverse. The 66-16 does have what they call "back tack" to reverse the direction of the stitches. Some machines that have reverse will have a stop on the stitch length assembly and when you move the lever it will reverse but keep stitches the same length as forward. I believe this is not the case with the 66-16, I think the back stitch could be a different length than the forward.
Janey - Neat people never make the exciting discoveries I do.