Hey Lanny,

Automatic or Manual wind movement...does not make a difference actually.

What makes the movement tick at a constant rate/beat is the balance/hairspring combinaition. We can adjust the gain or loss of a movement by actually making the hairspring a little longer (it will make movement go little slower), or by making it a little shorter (makes movement tick a bit faster)...so we can adjust this for let's say +/- 1 minute on the balance adjustment cock.

If a movement gains a lot of time, for example 4 minutes per hour or so...then there's obviously a problem with the hairspring. It can be magnetism as already mentioned by Jarl, and it usually also is magnetism. But it can also be "dirt" that makes the hairspring stick togehter at some places and making it actually shorter...so the watch gains a lot of time...

You can see with a good loupe, with the naked eye it's not possible to detect.

Best,
abel.