You got a good deal. I paid $40 for mine. I had to buy a new cord and belt for mine before it could sew, so that added to the cost. It came in the same case and had all the attachments and a couple oil cans. I like the knee bar. Do you have your manual?
Manual:
http://www.sew-classic.com/uploads/99K.pdf
It doesn't quite show the knee lever in the manual (it does in my printed one) - you put it in end pointing to the left and then it swings down into place.
Looks like this:
99K13 with knee bar attached
[ATTACH=CONFIG]240402[/ATTACH]