Oh no! Before posting this here I was the only one who'd played it, so thanks! I'll see if I can replicate and fix.
There is definitely a solution to all puzzles, if you're stuck then you've made an error somewhere and need to go back and change something. :)
Edit: Yep, there's a bug if a linked piece goes off the edge of the screen and a spark manages to randomly get there. Thanks for reporting.