I will remember this photo the next time I hear "I don't have the tools to open it" from a seller. This is one of the best answers to "how bad could it be?".
I often state I would rather untangle a hairspring than sell a watch on eBay. I would probably never put an Omega on ebay.
And I have a stem and staff for it to. Visible in the image I posted yesterday. Probably left over from when I repaired My Tissot T12 decades ago that was a loose box of parts when I got it.