1. Tools necessary for this chapter

BEWARE:  If you are installing this on an MK3S/MK2.5S, the instructions automatically take you here, which is the incorrect step!  Don't follow these instructions, scroll to 3B!The "Next" button on 2B should not lead here (3A), but instead should lead to 3B.  This wasn't clear until I was already taking apart my extruder assembly.

I followed the instructions perfectly but when I go to turn on the filament sensor it says that it’s “not responding” . also, Could someone tell me what this upgrade is supposed to do?

Title - This is for the MMU2S correct? - Please be clearer!

I agree. The assembly is fairly straightforward. But hunting for parts takes time. Even better would be if the parts were bagged according to the major steps in the assembly manual. That is how we bin parts during batch manufacturing. I also think that is how Prusa does it internally. I cannot believe Prusa techs spend time hunting for parts in different bags or bins when they are building printers. If they do that is incredibly inefficient.

There are lots of bags of parts here, so its VERY helpful if you could identify the name of the bags by the title written on the bags, instead of something like “bag of fasteners.”