In my rod building days, before I made any real money, one located the "spine" of the blank by placing the butt of the rod blank on a smooth surface. Supporting the rod near the tip with the open palm of one hand so that the rod is resting at about a 30-45 degree angle to horizontal. Using the other hand, applying a downward presure to the rod blank to bend it slightly. At the same time, rolling the butt of the blank on a smooth surface. This is what I meant when I said I looked down the rod to determine if a rod was wrapped correctly. As you do this, the rod will "jump" into a pronounced curve. The inside of the curve is the spine. You then mark the inside of the curve. On two piece rods (there were dang few multi's back then) determining spine on the tip section was important. According to my friends who still build rods, nothing has changed. Check out what the editor of RodMaker Magazine has to say about this subject. http://www.flyanglersonline.com/features/rodbuilding/tips/rt52.html Most of what I posted was taken from my copy of an old and tattered Flex Coat "Step By Step Rod Building guide", which I've had and used since 1987. That's some 20 years of rod building and everyone I know who builds rods is very careful to allign them properly. I'm certain the lower priced rods are not getting this attention. My purchase today of a TFO 2WT is a different story. The rod appears to have been constructed properly. When I get a 2wt line, I'll let you know for sure. As far as being able to determine through casting if a rod is correct, I stated one might not be able to notice (I might, depending on how poorly it was misalligned), however the rods casting potential would never be realized. This is a true statement. Some casters may never be able to throw 60-80 feet of line, no matter how well built the rod!