I am confused about the complications of an A7750 which is a pretty good clone of the valjoux 7750 movement, that is a expired patent movement that was a workhorse for many a SWATCH corp and other Swiss watches.
The only real issues were in modified A7750s where the seconds were adjusted from having their seconds sub-dial at the 9 o'clock position. Even some of those work quite well for a decent period of time, as long as they are kept clean and properly lubricated with the best lubricants for that use. AP ROO adjustment with added gears and in some cases an added jewel, jewels are much like bearings or the act as ways to stop the movement of a gear wheel as they can fit between the teeth without getting busted.
The other common modification is made to the Daytona watches as the seconds are normally at the 6 o'clock position. 8 extra gears are put into the A7750, and I have had one working just fine for almost 2 years. The 50th baby blue sunburst dial. All mechanical movements need servicing about the same frequency as quartz watches, but modified 7750s, need them about every 3-4 years and there are rules. Never put them on a watch winder, as you put extra movement on a modified movement.
Some may complain that with a few reps that the date well is low, but that is not universally true. Many watches are fantastic with them. I can tell you that many iWC with day and date plus chronograph movements are excellent with a good A7750. I can post pictures of my Top Gun doppel with ceramic case as an example. It was put on the sales thread about a month back, but not with any urgency. BTW, this is probably the worst time to sell, as most are hard up from holiday expenditures, while many want to hold on until after Chinese NY, because they think some new version or release is coming. some years this is correct on other years this is not correct.
The 7753 movement is a different chronograph movement that can be better with a higher date wheel, but with the hassle of having to press a indent on the case about 10 o'clock on the side to get the date set, unless you want to crank the movement through the whole month. This is what I choose to do. some reps keep terrible time with 7753's, but this isn't all to common. date usually is at the bottom 6 o'clock, but on the 3799 doppel Top Gun and the PAM daylight models it is more towards the 4:30 position.
Rules of 7750 or 7753 and most rep chronographs.
1. Have them serviced immediately as they are rarely lubricated properly and the movement factories can have loads of lint, dirt or almost anything, like eye lashes and hairs, in the movements, as their really are no "clean" rooms like those in the Western World exist. Hey even Apple has issues, and they spend serious coin trying to dress and ventilate everything properly.
2. only change the date when the hands are in the lower parts of the watch. Many swear that it is best if you have the hands at the 6 o'clock position, but that debatable. The tech and movement section has a ton of great information on this.
3. if you really want to use the chronograph function a lot, then spend the cash and buy a genuine watch of a loser priced brand, that if a swiss probably has a Swiss7750, or at least previously had Swiss ETA valjoux 7750 or valjoux 7751-7753. The chronographs can be used but its best to stop them between 10 o'clock and 2 o'clock, as they can get stuck or break if used regularly, as there can be a lot of stress on certain parts of the watch. The chronic needle is moving with quite a bit of torque and stopping it is rough on any metal that isn't up to par by any jewel not up to par. Thats probably a huge over simplification, but take a look at some eta teardown and you can see how the energy is passed through so many gears and torque of a good main spring to a less than good cannon pinion is a recipe for disaster every day.
Again most of the models, will automatically require that they service your movement and charge you for it before doing any other work, as some have been accused of breaking movements, years ago and we lost a lot of good models and repair guys over people pulling off casebooks, and almost everybody marks their work in a way that they know if you have taken the casebook off, since it was sent back to you. Most will replace the mainspring to a good one and the cannon pinion that holds the hands and chrono needle.
Again a ton of info is in the tech section, and you can go on you tube and watch plenty of valjoux 7750 movements being serviced, cleaned etc.
Its a misnomer to think that 7750s are not great movements considering that the patent on them has expired, and that means it is a very old and trusted design. eTA, and by association SWATCH Corp own valjoux. A genuine valjoux 7750 would go for over $500 now and the valjoux 7753 go for even more. They would never sell if they weren't a very good design.
They are a bit thicker than many of the newer Chronograph movements that some in house brands use. The Miyota-Citizen chronograph movements are a mm or two thinner, but the issue with them is that they are non-hacking movements....and we could go one forever about that and into high beat, mid beat and low beat and which is better or just more close to gen.
Anyway, if you think the valjoux 7750 is not a reliable movement, then you have now been corrected. If you want to use your wristwatch as a stop watch, and many do, a micro brand with genuine Swiss movement is probably the better move, but a quartz like a Tissot T-Touch or some Casio or multifunction 3V quartz is a much better option.
I am just setting the record straight on this.