Just my 2 cents- why don't you just take it to a watchsmith who can adjust a movement in 5 miutes and charge you $10.
BTW- I don't believe all these qc timing shots. They all seem to be +/- 7 seconds or less. In my experience the reps are not that accurate, especially the A 7750's. Also, 20 sec/ day MAY be improved but its not terrible. Remember
these are reps, COSC standards are about 6 sec/day. Many lower grade GEN ETA's don't do much better than 20 sec/day.
If you really want that kind of accuracy you're much better off with quartz. For under $300 you can buy a gen Bulova Precisionist watch with SMOOTH sweep quartz - accurate to 10 sec/YEAR!