z640 speakers, sound "off center"

[grasshopperbe]

I am having troubles with my logitech z640 speakers since a few weeks. For some reason, the left front speaker only plays very silently compared to the right one. when sitting in front of my desk, the sound is very notably on the right (really have to put my ear close to the left speaker to hear it)

i checked all my software settings(volume sliders, left/rigth sliders) , even tried reinstalling drivers but the problem remains, when i plug in my headphones directly into the pc, all is ok.
(dont have other pc speakers available to test).

I checked all the cables and connections, they appear ok. When i switched the font speakers , the problem was also still the same, so i would guess it is caused in the logitech internal amplifier somehow?
Is there anything i could try to fix this, or is it getting time to look for a new set of pc speakers?



in case i'd have to replace them i was thinking about someting like these (not really interested in 5.1 anymore as i never used the surround speakers anyway)

Logitech Z-3e 2.1 40W RMS Black € 68.00
Ozaki VA303 2.1 38W € 60.00
Creative Inspire T3100 2.1 29W RMS € 49.00
Ozaki VA403 2.1 48W € 70.00

it just has to do some decent audio when watching tv via my tv tuner card, watching online things like youtube, playing the occasional game etc. For music i use my home stereo.

Which would be the set to look out for in this price range?

extra info : my mobo is an asus p5k-e wifi, nv8800 gts 512, corsair 520w psu and antec p182 case

EDIT : while messing around with the speakers i think i found the cause. I noticed when i plug in the headphones on the center speaker, the left is also gone. but when i pull the headphone jack outwards just a little, and push it to the left, my speakers work normally again !. So i guess its a connection getting broken inside the center speaker.

Does anyone happen to know how to open up this speaker and maybe rewire it a little to bypass the headphones plug? i don't see any screws on it or so.