145.012-67 Hour subdial stopped working, help

Hard to say without having the watch disassembled enough to see the functions under the dial (that's where the hour counter is). Several possibilities comes to mind - hand blocked (no this won't stop the movement), improper adjustment of the hour recorder stop lever (brake), or not enough tension on the friction spring for the driving pinion that is fitted to the barrel arbor and drives the hour recorder runner.

There are possibly others, but those are the three that I have seen as the most common reasons for this specific problem. New parts might be needed, but everything in this area that is affected is readily available from Omega last time I checked...so the friction spring, stop lever, and hour recorder runner are all still available. Even the driving pinion is available if say something more unusual like teeth being sheared off is the problem.

Cheers, Al