Omega Mark 4.5?

This is really two questions.
1. I was the original purchaser of this watch in 1978 in Mexico. Bringing it home I hit it accidentally while doing some construction and cracked the crystal. The watch sat in a drawer for some 40 years. I went ahead and had the crystal replaced about 2 years ago. What I've noticed about the watch is that sometimes the date does not change properly and other times it does. Also when I go to set the day of the week, it does not allow me to do that in an normal way. One day comes up and then it stops and will not allow the other days to come up in succession. All other functions of the chronograph work perfectly.

Although thebwatch was not worn very much at all, in your opinion does it need a service anyway and I assume this is the only way to get the day date function to work properly? Readjusting the day date is not that critical to me and takes only a minute if it is incorrect. I'm assuming a major service for this watch would run in the neighborhood of $950. Thank you for any input.

2. Is it alright to hand wind the mark 4.5 on a regular basis if I am not wearing it regularly, but want to keep it running as I have a suspicion that the day date function might just need to be used more and perhaps might sort itself out? I have read that manually winding actually places an extra load in the movement versus simply wearing it. Is this true?

If the watch sat in a drawer for about 4 decades, it’d even need a service if the setting of the day worked perfectly. Otherwise you’ll just risk damaging more parts of the movement. For the same reason, you shouldn’t wind it manually until it’s freshly cleaned, oiled and possibly repaired.

Sounds like an overhaul would be your smartest move. The trusted experts here would tell you that just because it hasn't been serviced in a very long time, but even those of us who might not necessarily listen to them and go for overhauling all of our watches every 5 years as long as there are no apparent problems know that an overhaul is in order on a vintage watch with such an obvious malfunction. Official Time Watch in Utah will probably charge you closer to $500 than $950 for that. You can wind it by hand regularly. I don't even think it's expected that you'd never have to wind it by hand. Unless you're extremely active, I think it would eventually stop on you because the rotor alone will never keep it fully wound. My lay understanding is that the only things you really need to be careful about is getting it wet, force-pressing the pushers out of sequence, and setting the time/date/day in between 8:00 PM and 2:00 AM. Otherwise, it's a pretty sturdy watch. OTW will also restore the original sunburst finish on the case for not much more money, if you want to restore it to new-looking condition as long as you're already having it serviced. They did my Flightmaster about a year and a half ago and I posted the photos and paperwork in the FM thread.

Thank you all so much for all your advice. I'm definitely going to go ahead and have it serviced and I have just put it away now and will not use it again until it's fully serviced.