When I turn on the controller at the wall the number 15, then 30, then 03 come up in that order. The FS is on address 03 and now that you mention it I could not change that address when I first got it. Every time I tried to allocate another address the controller exhibited an error. I had no problem changing the address for either of my other two locomotives. I have no power clips on my very small layout so capacitors are not the problem. I use the Hornby power track for DCC, not analogue. I have had the FS for several months but always ran it when there were other trains on the track. But today, due to some work on my tunnel, I removed the other trains and was using the FS to check the opening size of the tunnel portals. That's when I noticed the problem. I hope there is a solution to this.