I don't know the model number but I have just done this job on a neff fan oven as follows, usual cautions about working safely and not alone:
1. You will need to remove the oven from surrounding cabinet. This was easy in my case: open door - locate two small crosshead wood screws set about 2-3" down from top of door frame in face of door frame.
2. The fan bolt has a left handed thread!
3. Having cleaned up the fan I found that it made no difference - the motor needs replacement. That's my NEXT job.
Rog
February 2006