Hi Joe,
Okay, I am totally confused. I did a search and am finding conflicting information as to which walking foot works on your VX-1120. One site says you need the SA-140, but another says that does not work on your model.
http://www.brother-usa.com/Support/Default.aspx
If you call Brother tomorrow I think they may be able to clear things up. I suggest that you tell them that you have tried a generic walking foot and the presser foot lever is hitting it. In looking at pictures your lever looks okay to me, so there must be a thin, low profile walking foot that would clear it.
Their customer support team is available at:
1-877-276-8437 Mon-Fri 9:00am - 5:45pm Eastern time
I am very frustrated that I couldn't solve your problem . I would have called Brother myself, but it was too late. Please let us know what they say, okay?