I have been playing around with different tools to try and find a good cheap way to adjust cen and pto carb screws - here's the best I found:

Harbor freight $7 4mm flexible screwdriver.

Then go between carbs and manifold (hard to see, but green handle on left is the handle for driver):

For trips you'd need two of em, but the real issue for me has always been the one behind the accel pump