Well, just to clear a little bit up, The new 7750 with whats called a "free sprung" balance dose not have a regulator, it uses weighted screws on the balance to adjust the arc of the balance wheel, turn the screws out, it slows the watch down, turn them in to speed the watch up.
When adjusting a watch like this one ( with a regulator) you can do it two ways, make the adjust mements at the gate ( the part you referred to as the "fork) or at the regualtor lever which if for a much finer adjustment then moving the gate.
When you adjust this what you are doing is shortening or leangthening the hair spring so that it's rotation is faster or slower thus making the watch gain time or lose it.
making big adjustments to get it into the ball park then you can fine tune it.
After you have worked with watches for a while you can do all the adjustments at the gate and not have to adjust it further.
Timing is a huge subject and this is the bearest of an exspanation.
Calix
