Ahhhh... I myself have not had much luck with the mystery movement. On my beloved 6263, I went through 3 - 4 movements, each of them with faults before swapping to the Swiss V23 to finally solve my troubles.
On the flip side, I also had a gorgeous PN 6263 with a perfectly running/winding fully ziggied movement that I ended up selling to kruzer00. To this day, it's still running flawlessly... So, sometimes it's just luck of the draw.
I would agree with Oli- Don't use the stopwatch too much, and I would also suggest the swap out to a genuine 24-703 Triplock crown and 7030 tube. The crowns that these watches come with aren't always the best- They tend to fail at the spring, and sometimes break free (hence resulting in what might feel like slipping when winding). Aside from that, you'll also benefit from having the Triplock in the numerous threading/unthreading when winding.