Omega 565 not fully winding

I recently received Omega watch using 565 movement. When I try to fully wind it at around 30 turns it does not turn stiffer but instead sounds like it would release some of the mainsprings tension.

I went through several posts but could not find a similar issue. Is this normal behavior for this caliber or is there some part which holds the mainspring broken?

I would estimate that the watch runs for about 30 hours and seems to keep time within 30 second tolerance per day.

Thanks, this pointed me to a right direction. Couple of other posta suggest it might just be a problem with lubrication of barrel where the mainspring is and I found a following post from other forum it sounds exactly like this: ”If you hear a "zipping" every so often when winding then this means that the lubrication in the barrel is not correct (or other problems) and the mainspring bridle is suddenly slipping to a lower state of wind.”

The watch has not been serviced in a bit more than a decade and I had planned to at least have it checked anyways. In general the appearance of the movement looks quite clean so hopefully it gets sorted out with just cleaning and proper lubrication.

Thank you for the tip. I did try to wind the watch again, just a turn or two before it slips and got 47 hours of power reserve. Perhaps just cleaning and lubricating all parts properly might do as it is loosing only between -6 to -14 seconds per day depending on orientation.