How and when are the hands on a watch locked into sinc w/auto movement?

[cjcar631]

The reason I ask is because I, as well as others, were experiencing what appeared to be the same problem with a certain brand watch. Shortly after purchasing it the movement was gaining/losing large incriments of time (minutes/day). At first I thought what most people were thinking... just a cheap crappy movement. But upon closer inspection I realized the minute hand was not locked into position even with the crown fully secured. All it took was a good shake of the wrist and the minute hand would move forward/backwards up to 5, 10, and even as much as 15 minutes at a time. After returning it for a new one I've had no such problems and the watch, although identical in all respects (exhibition case back), keeps great time. What would cause this?

[Rikki]

Hands are friction fit so either it wasn't pushed on all the way or it split because someone forced it on or or or or well you get the idea Rik

[cjcar631]

Many thanks Rik.