Just received my first set and was mildly disappointed. I found it difficult to keep the units together out of the box and tried a dab of super glue. Then I realized the wiring did not make good connection to the tracks.

My remedy was to:

-take the plastic stop piece off the rails

-snip off the end ties from the tracks

-with the lights in place and wires pulled tight through the plastic then I soldered the wires to the rails

They seem to work fine now but look a little rough. If I was better with the soldering gun it would have snapped back together better but I got the assembly a bit hot so be careful.