Gosh, I can't believe, I got it! :)) In desperation I went back to Railgun and did it a few more times. Then, somehow, this one ''opened'', too. Levels like this make my brain work huge time. :)
This level is so much worse than the reviews make it out to be. There's several different initial setups that lead only to 90 step paths. Dozens and dozens of 2-off solutions... brutal level, but satisfying to finally solve!