> http://www.rinkworks.com/rinkforum/view.cgi?post=44282
>
> and
>
> http://www.rinkworks.com/rinkforum/view.cgi?post=43004
>
> both were extremely helpful with the puzzle. However I had to cheat to get the answer. There was no way in hell I was gonna try 4 combos, all of which seem to work [in theory].
>
> However, gremm says there is only one solution and I don't see how that's possible: If M16W could be outer and south, couldn't it just as easily be outer and north, or inner and north, or inner and south? Then all you'd have to do is change the other conduits accordingly.
>
> I mean, the way it is set up gets you a groovy nuclear symbol, but whether M21 loops outward or inward, there still is gonna be a broken conduit.
>

That's exactly the problem. Since the conduit across M21 from east to west over the outer parallel is broken, you can't use it. That rules out two of the four combinations. Of the remaining two, one is ruled out by using the other broken conduit.

Actually, you have a unique solution no matter where the two broken conduits are, as long as one's in the north-south direction and one's in the east-west direction. If you had two broken conduits in the same direction, you'd either have two solutions or no solutions.