Carrera 1964 Re-Edition Gasket

I’m looking into buying a Heuer Carrera 1964 Re-issue, but I noticed that the gasket is missing in the picture on the sales post. Is this a red flag, or an easy fix? I’m not yet quite familiar with the intricacies of watch tinkering (yet I doubt this is this very challenging), but is this something I could purchase and easily replace? The movement is the Lamania 1873. Reference number: CS3111. Thanks so much!

Unless the seller is telling you it has been recently serviced, I wouldn’t necessarily consider that a red flag. I guess it depends on the asking price and overall condition of the watch though. The oldest CS series Carreras are nearly 30 years old now. Gaskets don’t last that long.
Great watches. As close as you can get to a vintage Carrera without the vintage price. I just broke the mainspring on my CS3111 but it’s only the second time it’s stopped working and I’ve had it for 20 years.