Re: 1926 NH carburetor
If working on T's, you should get a re-print copy of Model T Ford Service, that is the complete repair bible for the T by the Ford Company. Details on the NH are in this book, which covers in detail the 1924 car , and Improved Car '26-'27 , but is good for any year T. Get your copy, 296 pages plus hundreds of photos, from any parts vendor for T parts. Carb Overhaul is in Chapter XXVII.
Here are some pics, the first one shows the tiny vents, these are plugged on the outside, remove the plugs and clean out the vents, then re-plug with small dia brass rod. The rest of overhaul is replacing the needle, seat, float needle and seat, and being sure the butterfly work. Then set the float to factory specs.