Just returned from GIE where I attended a diaphragm carburetor training session given by Stihl. The training instructor recommended getting JIS bits or screw drivers to work on these carbs. He said, and I can confirm this, as we used JIS bits to tear down the carbs, that they fit the cross screws better than regular phillips drivers and will not cause cam out and stripping of these screws.
Here's some links
https://www.amazon.com/Vessel-Megadora- ... 8MH70VR4SF
https://www.vesseltools.com/
Vessel tool number for just bits: A-16621
#2 part number 421241
Enjoy
R