How do I fasten Neff spray arm?

I have a Neff S5453X0GB/19 dishwasher. Worked fine until yesterday when we found the upper spray arm fell off. We can't seem to find any way of refastening it and the manual is no help. Can anyone advise?
Selwyn Ward, September 2005


done
Not absolutely sure if same model as my NEF but...
when you pull out the upper tray do you see the tube which is in the centre of the tray? Are there two notches in the top of the tube?

Jules, January 2006
link Click here to see other fixes for Neff.