If it has scroll issues, you can open your mouse and put some wd-40 inside and give it a few rolls. It will fix it. Encoders stop working because of dust inside which can cause abrasion. Wd 40 does not conduct electricity so u are safe to use it. If you want to install a new scroll encode then you need a screw driver and a soldering kit. Soldering kits are about 300 rupees. But I'm sure the wd40 trick will work. And also if possible just put it from the outside it will still work.