I use my Leigh jig infrequently and find that I have to "re-learn" how to use it each time. I made my test cuts and got a tight fit after a few tries. I noticed that the left edge stop on the top of the jig was offset about a 1/2" to the left compared to the vertical left edge stop. The manual goes through a procedure to make sure the 2 guides are aligned exactly the same. For the life of me I don't remember why I have this offset but I haven't touched the jig in a couple of years and my last set of drawers turned out fine. If it matters, I always cut half blind dovetails.