Could get $3500 - $5000 for it easy.
Sold!
Might be the mainspring. Might also be lots of other things. Like people have said here, look for a smaller to take it in for a service.
I think the movement in this watch will be cal 1481 - a movement Omega jointly produced (and shared) with Tissot. You see it in Tissot Seastars from the same era, they call it cal 2481 though.
Does the date jump forward when you “click” the crown in?