Has it ever been sent in for service? I finally sent in my chronomat evolution, purchased in 2009. It needed a main spring and one other part. Even though it still functioned...... Also needed a polishing. Yours looks like it could definitely use a polishing. Unless you're really famous, (Paul Newman's Daytona
) polishing won't decrease the value. So, it may improve your resale. I didn't send mine to Breitling, but a very good authorized repair place. Still a bit pricy though. $760 plus the shipping.