How to mod a Surly Tuggnut chain tensioner to work with Campy 1010 or similar horizontal dropouts

I am told that this mod is not necessary to make a Tuggnut work acceptably on horizontal dropouts, but it seems to me that it provides an extra level of security that can't hurt.

This diagram is a bit messy but clear enough I hope. The actual mod is stupidly simple when you see it in person, it's just a bit tricky to describe.

(1) shows a Tuggnut in normal operation. Note how when the track nut is tight it holds its position very securely---because the bit of metal is poking into the end of the track ends, it win't swivel up or down, and of course it can't go left or right because of the axle nut's tension. After my mod the Tuggnut is secured against up-down motion according to the same general principle, but this time by poking a much smaller piece of metal into the little hole in the back of a Campy 1010 or similar dropout, as seen in (4). (2) shows the area of the metal bit that you take off with a round file, after removing the bolt. (3) shows what the thing looks like after the mod; notice that a little knob is now sticking out. (4) demonstrates how the modded Tuggnut interfaces with the dropout's little hole. The mod works with any dropout that has a hole like this. I made sure though that the metal bit is still able to press against the back of the dropout as seen in (4) (this is the reason for the round shape I filed out), and that the little knob is not actually pressing on the inside of the hole.



(this cut off text says "you'll need to remove this little collar first")

I destroyed my retaining collar in the process of removal, so now the metal bit is free to come off the bolt. I bet I could find a new one but in practice it isn't really needed; when the wheel is off and the Tuggnut is still on the axle, gravity pulls the Tuggnut so that the bolt is pointed up and the metal bit naturally stays on.