Thanks for the feedback!
You didn't find the sprite change indicative enough? They all seem like broken...Please help us improve it! :)
I found that If I get focused on keeping two low-energy elements powered, I can easily miss when one of the other elements gets damaged. I do notice it after several seconds, but usually it's already too late. Having additional marker would help in those situations, when you're frantically trying to keep something working. :)