http://www.overclock.net/t/1485192/steelseries-sensei-scroll-wheel-jump/10" said:I FIXED IT!!
Steelseries Sensei RAW
Had the same issue, every 8 wheel clicks, the mouse jumped up. I lost my receipt so didn't even bother contacting Steelseries.
Sorry for the lack of pictures in the early stages, I only realized that I could actually fix it once I realized what the problem was.
1 - remove the plastic gliding pads at the bottom, screws are underneath (I used my nail to start, the glue is sticky enough to apply back on later during reassembly, though a hairdryer could help)
2 - disconnect the cable linking the upper PCB (grabbed from both sides and rocked gently sideways while applying upward force)
3 - remove the wheel led, the led's pcb is just resting on 2 little pins, you just have to delicately lift, and once the pins are cleared pull outwards
4 - Remove the 2 screws holding the main PCB (not crucial, but I found it easier to handle the next steps)
5 - unplug the cable that comes from under the PCB
6 - lift the PCB out of its pins
7 - remove the wheel, it just falls out towards the right
8 - use an exacto knife then tiny flathead screwdriver to lift the 4 tabs holding the "small wheel" assembly - lift all 4 tabs enough for the black piece to be able to bend away from the metal side.
9 - once you have spread the black side back enough, push the bent metal clicking piece towards the metal frame, and the plastic mini wheel in the middle so that you can extract that mini wheel.
Once out the wheel looks like this:
At this stage, you can see inside the mini wheel's assembly that it has 8 small contact pieces and a longer one, and that the wheel has 3 contact pins making contact with those. You can also see that there is some nasty oil that has hardened. My guess is that this problem occurs if the pins lose contact with one of the small strips at some point, perhaps due to the pins not pushing hard enough against them, or having poor contact because of the apparent excess of oil.
10 - use a small flathead screwdriver with a clean thin rag on top to clean the oil off the contact portions, and VERY DELICATELY bend the 3 arms on the wheel up a little, to make more positive contact. I just slid my flat head screwdriver under from the tip and rolled the screwdriver sideways to lift the pins in a slow controlled manner. When I was done the pins rose just enough so as to be visible when looking at the wheel from the side.
11 - reassemble everything, done
Mine works like a charm now, I hope this helps someone!!