I suspect it's going to be something that needs to be tightened up.
I wonder if it became loose at one point and pivoted, and now it's wedged.... hmm,.. I'd really like to see a pic when you have a chance.
If the worst case happens, and the part is broken, it's still available here and it's not that expensive:
http://www.sewingpartsonline.com/act...g-machine.aspx
I've never used these guys, but they seem to have good prices (my cdn cost on the part is over $10, so their markup is reasonable), and good pictures on their site so you can tell that what you're ordering is what you want...