There are a number of things that can cause a walbro to "flood". Buck mentioned a couple of items above that will cause the problem and also the rocker arm that moves the needle can get bent up too far and cause the needle to stay off the seat when the diaphragm and cover are installed. Like you said, do some research on the walbros and you will find a wealth of information. Also, the kit for these little fellows comes with a new needle, rocker, rocker shaft and many other parts including new diaphragms and they can generally be found for less than 10 or 12 bucks. My friendly neighborhood lawn mower shop sold me mine for $7.95. Good luck with the Tigre.