Yes, Niki is right here. I should have mentioned in my post that the string binding that I experienced when moved from .9-42 to 11-49 was due to the rough groves. There was no need to widen the slots. What I did simply is I took some old wound strings and used them as the file to smooth the slots (don't own any fine/small files). This job requires a lot of elbow grease because strings are not files and you have to be careful not to mess something up. Later I used Niki's wax floss trick to "grease" them up a bit and that did the trick.