mainly just do a reverse of the feed back. If that doesn't work it gets a bit more difficult by using different chip sellers and searching the feed back number with a Ctrl "f" scanning through 200 feed backs at a time in a matter of a few seconds, it may or may not work but found many like this. I really no longer keep track anymore, the fun is kind of gone out of it. BTW the ctrl "f" I use for articles and everything else. A super fast way to locate what you are looking for in an article. especially if it is pages long.