I have noticed that many many Accutron 214's have movement years different than the caseback year by over the acceptable plus or minus 1 year. For examble, I see casebacks with a M3 mark and a movement marked M7. I would say I see a mismatch 40% to 50% of the time but that is just a guess and could be a little high. My question is: Did watchmakers, back in the day when Accutron parts/movements were readily available, simply change out movements with new ones rather than go through the process of actually repairing the watch? Were complete movements purchased from Bulova pre-phased so the watchmaker didn't have to do that?