I asked my mechanic to lean the mixture a little since it has been running rich. The mechanic told me that he could not adjust my main rack because he could not get his screwdriver blade to engage the adjustment screw.

Although I have never done it, I wanted to try it myself. I followed Leslie F. Rice's article on Pelican website and made a small screwdriver out of a 1/8" steel rod about 22" long. After removing the 5 mm Allen screw, I tried to engage my homemade tool. I could insert my homemade tool about 1.5" into the hole but cannot feel it engaging the adjustment screw. With very little force, I could push the tool further into the hole; it felt like I was push something that was spring loaded, but no engagement and no click when turn.

Any advises from the board are greatly appreciated.