Sounds like you solved this, but figured I’d add my experience for anyone else dealing with a dripping carb. My 40 DCOEs were purchased new and were pooling and dripping from both carbs for different reasons for the first couple months of running them. I discovered that the front carb had a slightly twisted Venturi because the set screw on the side of one of the throats was not seated correctly out of the box. That was an easy solve once I noticed what was happening. The rear carb was a bit more frustrating and leaked way worse. I’ll spare you with all of the details and attempts to remedy this including several phone calls with the supplier. It turned out that the rear carb had heavier plastic floats than the front carb. I weighed it with a postal scale and found it to be almost double the weight of the non-leaking carb. It was either saturated with fuel, or just heavier for some other reason. Not sure. But I replaced it and my problem was solved.
Just because they are new, doesn’t mean that something can’t be wrong with them.