patrick_y[PuristSPro Moderator]
33643
Reliability issues...
ZW has a lot of reliability issues, as it's an incredibly complex watch. The acceleration of the discs during the minute change is violent and requires a fast acceleration and fast deceleration. Most problems arrive from the disc change mechanism. Sometimes disc(s) will become misaligned. Sometimes the watch will just stop advancing time.
I have wound both old and new ZW watches back to back. The newer ZW is significantly easier to wind than the older ZW. But still overall significantly more difficult to wind than a normal watch. So a normal watch is easy to wind, a new ZW is difficult to wind (two orders of magnitude more difficult than a normal watch), and the old ZW is very difficult to wind (one order of magnitude more difficult than the new ZW and three orders of magnitude more difficult than a normal watch)!