OK, I'm only 3 years late in answering this.
I have a vornado VH101 and have a similar problem. I will describe my problem; maybe your issue is the same or maybe not.
The fan blade attaches to the motor by friction. After a while it slips forward and hits the front grill and makes scraping sound. Eventually it gets stuck on the front grill and won't turn.
The temporary solution is to push the fan blade back. I took mine apart (4 screws, including one that requires a special screwdriver) to do this. Be careful not to push the blade too far back.
BTW, the VH101 is recalled. Don't know about the VH102.