neff oven element replacement?

The element on our neff (naff?) double oven has failed yet again (4th one in 4 years) and I was going to replace it myself. Have removed all the screws but cannot access the last screw behind the fan blade. How can I remove the fan blade as the central nut is VERY tight?
(It would help if the fan blade had a cut out in it to access the screw)