Oh boy! I have an Electrolux ER 1380 and thought the cover must clip on. I then spent three years using brute force and ignorance to no avail other than detaching the whole light unit! Thanks for the reply above - after having detached the whole thing I found the screw UNDERNEATH the translucent casing! About halfway along as the answer above says. Top marks for the strength of the Electrolux plastic. I had tried to break the casing to no avail - thank goodness.
Light now working. Amazing!
James Lizard, May 2010