I sent my SBGM029 to the local Seiko service centre in early August as the movement stopped and could not be re-started. They told me it needed to go to Japan and I said yes, never expecting it to be back before Christmas.
Lo and behold - barely 6 weeks later, it's ready. I just collected it today and it came with a full report in Japanese and English. Basically they replaced the escapement and overhauled the movement.
Great service from GS!