Eheim Pro 4+ 350 - part found loose inside

[Hjnlssmith]

I have the above cannister filter and have been using it for the last year with my 75gal tank. Works great and pretty pleased with it.

During the last cleaning, I found a little white plastic piece resting inside the filter cannister next to the blue filter sponge. It is part of the assembly identified as part number 7428728 (see included diagram below). I cannot figure how to reassemble the parts and install them without the white piece (bottom piece of the assembly in the diagram) falling off. What am I doing wrong. Have been running the filter without this for now until I can figure it out. Help.....

 

[blaxsun]

I'd drop Eheim a line.