Welcome.
I'm guessing that you do not have a manual. Maybe you could get one at
http://www.sewusa.com/Sewing_Machine...w_Home_672.htm I have been working with a machine that uses cams and one has to move some knobs or levers to insert the cams. It looks to me that the "cam follower" is in the wrong position as indicated with the arrow.
[ATTACH=CONFIG]595904[/ATTACH]
Try moving some knobs and seeing if it moves. Have you tried removing the cam and does the lid stay closed?
You might check
New Home sewing machine model 672 It is an older thread and don't know if she still has the machine.
Janey - Neat people never make the exciting discoveries I do.