Ron, the center metering valve on a Duplex carburetor has a riveted-on tapered stem I call an umbrella. This fits down into a tapered seat in the carburetor body. This seat is commonly made of brass and has two holes that are "square" to the carburetor. These holes feed additional fuel to the main nozzles in addition to the fixed jets. The book suggests to bottom the tapered metering valve in it's seat and then back it off an appropriate number of turns (commonly in the range of 2 to 2.5 turns out). The "umbrella" is made of steel and as mentioned is riveted to the metering valve. It is not uncommon for the seat to be turned in too hard and the umbrella sticks to the valve. It then comes apart from the metering valve and then you have a mess. I have seen this happen many times and have also noticed the seats turning in the carburetor bodies. The seat has two marks on it that look like a screwdriver slot (they aren't). If the seat is indexed correctly in the body these slots will be "square" to the carburetor as well as they line up with the holes. If the seat has moved the carburetor will not allow the tractor to run or pull like it should. This is a very often overlooked item on a Duplex carburetor. Hope this helps. Mike
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Today's Featured Article - Identifying Tractor Noises - by Curtis Von Fange. Listening To Your Tractor : Part 3 - In this series we are continuing to learn the fine art of listening to our tractor in hopes of keeping it running longer. One particularly important facet is to hear and identify the particular noises that our
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