I just had one of my two replaced a month or two ago. It was a tad over warranty, but I explained to them I had emailed regarding the issue when it was still under warranty but was ultimately able to get it working without having to send it in, but now could not. They sent me a brand new replacement device, which I was appreciative of.
Now my second one I find locked up and not spinning. After a 2 hour Muriatic acid soak, still nothing. It will start to spin for 2-3 seconds and stop. It's of course just over the one year warranty and frankly I don't even want to waste my time emailing them and sending it back. I clean the pumps with citric or muriatic acid every 90 days, but I'm really not impressed by these pumps.
I think I'm done with the Neros. A 100% (2/2) failure rate at around 13 & 14 months respectively isn't very impressive. I think I will look into another MP40, Tunze or Jebao as you hear of much lower rates of failure with them and mine all work flawlessly.