I have received and gone over the lists of carbs, both Zama and Walbro, but when looking for the carb that I have, I do not see it listed. I have seen other carbs, but what I belive to be the vent hole will not match up with the back plate. Here are some pics of my Zama and the back plate. Any ideas? Is that a vent hole that must match up with the carb? Just consider me new, and confused!