slight klunk noise inside the rear of the car "HATCH WEIGHT"??

Has anyone else heard a slight klunk noise inside the back of thier gen 2? I've taken apart all the paneling used foam tape to secure things and took apart the spare tire area etc and the klunk persists. It seems to vary intensity every time I close the rear hatch.

I now suspect this thingy I found mounted in the center of the rear hatch under the plastic:

04 05 06 07 08 TOYOTA OEM PRIUS HATCH WEIGHT SPRING: eBay Motors (item 260681374047 end time Nov-20-10 13:01:55 PST)

The ebay seller calls it a "hatch weight"

What is this thing?? At first I thought it might be some sort of crash sensor, but now that I see it has no wires...

So Toyota made the rear hatch too light? Perhaps this helps the hatch have the momentum it needs to positively slam the latch shut?

Mine flops around pretty easily inside it's casing and may be my noise that's been driving me nuts.

 

I stole the picture from the auction, that's not mine. If I needed it I would not hesitate to buy that one. Rust does not matter, this part never gets seen.

Just curious on what you guys thought about this parts exact function. I mean if I stuffed foam around it to see if it's my noise, would that be a problem? It really seems wierd how they have a weight floating around on a rubber mount in the rear hatch..

Anyone?

 

It's under the large plastic panel on the back hatch. The panel is clipped in with plastic clips and pops off. I have not had a problem breaking the clips but have purchased extras because I know how these clips are, they break easily. If you've replaced your rear hatch switch due to the melted gummy problem or tried to trace annoying rattles you may have looked right at it and not known it. I thought it might be a strange airbag/crash sensor, then I noticed it on ebay and got a good look. I remember seeing it in the center of the rear hatch door.

Now I just can't beleive a part like this would exist, it seems nearly useless. The only possible use I can think of is to insure a positive closure upon slamming the rear hatch. The residual force from the suspended weight would probably apply a bit more force over time after it's slammed shut. I've never seen anything like this.