I assume the parent means to adjust the watch internals - changing how fast or slow it runs, and completing basic servicing. I have a couple of automatic Seiko

I assume the parent means to adjust the watch internals - changing how fast or slow it runs, and completing basic servicing. I have a couple of automatic Seiko's and they keep terrible time despite (fairly expensive) servicing, and they are made for home adjustments (though that doesn't stop a lot of people having a go).