Thanks again, and slighlty ironic that you are one of the sources of my thinking I needed to check SN in Target as March '19 you had posted:
I bought a Phonak Roger 10 off eBay. The serial number doesn’t seem to work when I put it into the Target software.
When I put my Roger 10 that I currently have, it comes up with the warranty details.
I looked with a light and a magnifier. I’ve definitely got it right.