So...bought a new lens - Sigma 70-200 2.8 OS and generally speaking im very pleased with it, but iv noticed one small (maybe problematic) issue..
When the lens is pointing down the zoom rings stops being smooth and starts to jitter when I turn it. Im guessing this is because the glass element inside the lens is (due to gravity) pushing down and forcing the zoom ring to kinda stick.
Im not overyly worried about it, but if its a sign of a larger issue ill return it while I can. Iv also never owned lens quite like this, and im unsure what to expect - so any advice would be great 
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