help me buy the right screw bit

@sneed M1.6 x L1.7 means that the screw has a metric thread, is 1.6mm in diameter and that it is 1.7mm in length (measured from the bottom of the screwhead to the end of the threaded part). It is not related to what tool you need for removal. That is depended on the screwhead. According to the illustration in the maintenance guide, it is a PHillips Screw head. I suggest that you get a good toolset, at least something like this Mako Driver Kit - 64 Precision Bits Screws like the one you are working on, commonly use threadlocker to keep them secure. That means you need a good fitting screwdriver and apply some downward force while trying to turn the screw.