I've bought a cheap used package of a Nikon D3100 and some lenses, including a Sigma 17-70 f/2.8-4 (not 4.5, and not contemporary). After several tests I can tell that this 17-70 has a problem. Here it is :
on any body : stabilisation behaves strangely, like "punching" hard the image to the side instead of a gentle adjustment
on D3100 : when the lens in mounted, horizontal scanlines (like old TVs) appear, in low light globally and bright light on dark-colored regions, in live view and on pictures taken. When half-pressing the shutter button to autofocus, the screen glitches with weird colors and huge scanlines. Last but not least, the camera shows a low-battery indicator even when fully charged, and when mounting another lens a full battery is shown
on my main D5500 : autofocus does not work at all. The display flickers between M and AF. And I talk about 7-8 swaps a second. No scanlines here, no glitching screen when half pressing in manual.
on my dad's D5200 : no problem at all except the stabilisation problem ! AF works fine, no glitch, no low-battery warning.
I'm lost there as the problems are inconsistent from a body to another. I feel like the stab could be the culprit. I would like to sell it back and have no budget to send it for a repair (it's worth 160€ used at best...), so if someone has a clue what could be going on, I'd be very interested to read about it !