The problem with the crown and tube on the rep 'Historic' Radiomirs is that the metal used to construct these components is a soft metal- Possibly brass. So, it is recommended that you take great care and caution in threading and unthreading the crown each time you go to wind the movement. Over time, and since the movement is handwind, stripping may be inevitable as wear of the material over time cannot be avoided; however, it looks like davidsen might have a solution for us with this problem in the form of better, stronger tubes and crowns (see olreon's thread in General Discussion)...