I don't know about the DFP problem, but respecting the Momo Racing centering problem, I had the same problem more than a year ago. Don't try to ask on the message board of wingmangteam, they'll tell you that the problem is dirt on the disc on the optical sensor. It could be a dirty sensor... but at least it wasn't my problem (tried cleaning the disc with almost everything (included canned air), with no success. (Here is the post where I asked about it: http://www.wingmanteam.com/dis ... June620040745am#POST12840 (posts on the thread reads from bottom to top))
Personally I recommend to everyone with this problem to ask for a replacement (either to logitech or to the store), and see if you're lucky and get a wheel without the problem (If there are one.... (I got a replacement, but with exactly the same problem... :doh)
Finally I was able to eliminate the problem from both wheels.
My conclusions are that there are 3 possible causes for this problem :
1> Dirt on the sensor
2> The disc on the sensor being loose
3> The "sparks" produced on the motor EM-interfering with the sensor.