... this past month has been screw problems month. Broken, loose, missing, cross threaded, stripped threads and screws that fell out during shipping.
This is my Heuer 12 tachy R72 that I worked on last month. Both of the screws in the crown wheel core were very loose making it very hard to wind. The seller said everything was "working perfectly" - sure! These are frequently loose and need to be checked every time the watch is serviced.

This next pic is of a cal 11 Autavia that lost a screw during shipping across the US and stopped the movement. This screw holds/guides the coupling clutch and rarely needs to be removed so it was odd that it fell out. Upon a closer check after it was returned, there were 4 other screws loose in the bottom end of this one.

Here is a broken screw that I just found this morning in the coupling clutch of a Clebar R72 movement. Another one that normally does not need to be checked because they are rarely ever removed.

I have not found any loose screws in this last movement but I thought you might like to see it anyway.

From now on I will be checking EVERY single screw in EVERY movement that comes my way!