So, here is another model that no one else will ever need... but if you do, here it is.
The carburetor setup on a Poulan P4018WT/802036 chainsaw has a very unique design. This carburetor (a Zama W-26; part # 545070601) utilizes a throttle butterfly separate from the main body. This butterfly is activated when the metal pin attached to the throttle cable pushes on a lever attached to the throttle butterfly shaft.
My customer broke this lever while trying to replace the fuel lines himself. Unfortunately, this lever is not an individual component - you have to purchase a complete carburetor unit. Well... most people do. If you're handy with FreeCAD and a 3d printer, you recreate the broken piece and print yourself out a happy customer :)
This will fit snugly. You will have to tap it on the shaft. Once it's on (don't forget to replace the spring before installing this), you will need to mushroom the end of the brass shaft slightly to keep the lever in place.