Need help on identifying a vintage model

[Harikrish]

Hello,

This is my late father's watch. He got it from my grandfather. I am new to this. Would anyone be able to give more information on this model and the vintage it is from. It's running fine except the day adjust isn't working. I don't see any numbers written anywhere except for 20mm near the lugs.

Thanks

 

[vienna]

Looks like this model,

kind regards Max

 

[Harikrish]

vienna

Looks like this model,

kind regards Max

Looks like it. Thank you so much Max

 

[JwRosenthal]

I’m not sure if this was one of the movements where the day was changed by pushing in on the crown and then pulling it out and quickest for the date. If the crown sits out from the case 1mm, try pushing in towards the case and see if the day flips. Regardless, a service should sort it out. It’s a lovely family piece and these 70’s Omegas are groovy.