is a reworked Valjoux 7750. What you are experiencing is a known feature of that movement, "Valjoux wobble". The rotor winds the movement in one direction only and "freewheels" rapidly when it starts moving opposite to that direction. It is absolutely nothing to worry about. Once you know is not dangerous it can actually be a fun thing. I know what you mean though, when I just got started with mechanical watches three years ago I bought a watch with the wobble (a Max Bill Chronoscope) and it irritated me so I brought it right back to the dealer!
Best
Andreas