My son killed a redhead a couple years ago with a slick band. Nothing legible on half the band. He was afraid to send it in thinking he would not get it back or it would be lost in the mail.
A forum member posted a how to using acid from home depot. I followed it to the letter and it worked perfectly raising the numbers where they could be read.
Entered the info on the website. Duck had been banded 8 years prior. I think the salt water is hard on them