VBREDSOXFAN welcome to SMF and congrats on your New MES 40, also welcome to the MES owners club here.
It isn't difficult to discern if chicken wings are done, but a question first.
Are you breaking down the wing parts before cooking, thus are you cutting and discarding the wing tips, then cutting apart the upper arm (single bone) from the lower arm (two bones)? Or do you leave the upper and lower arm attached and just discard the wing tip?
Personally for bbq and smoking I discard the wing tip and leave the upper & lower wing arms attached, this makes it easier because one turn you are turning two pieces. However if I'm deep frying the wings, I separate the upper & lower wing arm, like most restaurants serve the.
First the appearance needs to look cooked, if you are leaving the upper arm & lower arm attached, try pulling apart the upper/lower arms, if they come apart easily they are done. If the meat feels like it has a rubber band attached to prevent pulling apart then they are not done. Also you can take a fork and try to pull meat away from the upper single bone arm, if the meat comes off easily they are done, if the meat resists and you have to dig in a pull hard they are not done.
Sometimes, some of the wings will be done and others are not. I like to take the ones that are done and stack them on the ones that are not done, so on the grate side of the wings not done is getting exposed to the heat and the other side which has the done wings sitting on them, the heat from the done wings is helping cook those wings not done. Or you can simply remove and foil the done wings and just cook the rest. However usually it is only another 3-5 minutes before those wings not done are finished.