Needle Guard Adjustment Screw

[friquant]

I hadn't noticed this before, but I think it's an adjustment screw for the needle guard. (Jianglong 341)

 

Looking closely, I could see a hexagonal shape behind the round hole. 1/16" (1.7mm) hex wrench seems to fit.

Or from a different angle:

Here I removed the needle guard and you can see the set screw that sits behind it:

 

I've been wanting the needle guard to be stiffer anyway. (What good is a needle guard that just gets out of the way when the needle comes by?) Using this adjustment screw will mean there is a support closer  to the bulge in the needle guard, so I expect it to flex less when the needle presses against it.