Hi. You can visually check intake ducts, poor anchors, dry, cracks. One of the points on the carburetor is the plane of its deformed base or with a poor seat. The technician or mechanic uses a vacuum gauge for carburetor adjustments, or a carburetor cleaning spray spraying dubious sectors, where the gear will vary, however this method should be used by experienced personnel since it is dangerous because of the reaction it can cause. Take a transparent piece of duct, place it in the ear and with the other end look for possible leaks, this simple method will act as an oscilloscope. Salu2.