I have one neg. too. It's not so bad for at least two reasons:
(1) I always figure that those with a 100% positive rating never leave a negative for fear of getting retaliation and having their perfect record "spoiled." No honor in that.
(2) It's like getting a scratch on a new car. Once it happens. you can operate more freely and less worried.

I believe that once you get 999 out of 1000 as positive, your average rating that is shown goes back to 100% insteaqd of 99.9%. So you have something to live for.

Robert