Ahhh, the coupler tube... For the AeroTech Mirage that I built, I actually had to peal the white covering off the coupler tube. Well, here is what I did: I took an xacto knife and cut the through the top paper layer on the coupler leaving approximately a 1/8" ring un-cut. Then I peeled the white paper off of the coupler. Only the first layer of paper needs to be pealed. The end result was that it was too loose so I wrapped masking tape (one layer) around the peeled tube. Now, when I slide the two body tubes together they slide together easy, then when the 1/8" un-peeled section is reached, the tubes fit snug. It worked out well. I hope this makes sense. I will try to take a picture tonight if I can remember...