2. What is the issue of the A7750 second@12 movement and how can one overcome it?
In short, Friction. The natural second@9 is brought to the 12 o'clock position by a series of transfer gears, which increase the friction across the gears and the alignment of the gears are often imperfect, especially in older batches. The design, while conceptually brilliant, lacks the quality parts and execution finesse required for all the extra gears to run smoothly and consistently. In the recent batches, this issue has been improved somewhat. Other implications brought about by these transfer gears are erratic chronograph use and a thicker movement as a result (about 1.8mm thicker than the A7750 movement). A movement service coupled with the replacement of the asian mainspring to a swiss one can help to alleviate the friction issue, but will not be able to completely overcome the design of the movement or movement parts misalignment. When you send in a rep ROO with the A7750 sec@12 movement for service, the expectation needs to be managed right. The movement can be cleaned and oiled and mainspring replaced but the design of the movement will remain precarious by design. The chrono function should be avoided as a rule. Yes I am aware of members in the group who have successfully ran their chronos without issues multiple times but really you do so at your own risk ultimately.
