This is a TQ, right? The most problematic thing with them is the main jet wells in the bottom of the plastic body. Here's how I do it. I get a small pair of pliers and grab the main wells and gently pry back and forth. If they pop off, I clean as much of the cement off as I can without removing any plastic. Then I use a product called Seal All.
It's resistant to gas and oil unlike JB Weld. Be careful though, it's kinda runny so use a small brush and apply it. Apply it to both the main body and the the main jet wells and reassemble, then brush about three good coats on the outside around the seams, letting it dry tacky to the touch between coats. It doesn't take long.
Now, if the main jet wells will not come off after gently prying, just coat the seams with a few coats of the seal all on the outside of the seams like I just described. They'll never leak again if you use that product. Like I said, it's runny so be ready for it. You're not gonna think it's gonna do anything but that stuff is badass, it'll work.