I asked these questions on the "Grand Seiko" forum 2 days ago and received no replies so I thought I would ask here,... the present GS Japan site indicates the adjustment steps of the 9F series HAQ movements to be 6SPY. Several posts I have read on this site indicate the adjustment steps to be 8SPY. Quote from Seiko site (in blue text below):
What is a regulation switch?
There are several ways to adjust the precision rate of a mechanical watch and the most reliable is the regulator, which makes fine adjustments to the balance spring’s range of motion. The Grand Seiko team recognized its value. Caliber 9F also has a regulation switch with plus to minus graduations marked on it. This mechanism adjusts precision by switching the circuit to make corrections after a designated span of time. Let’s remember that Caliber 9F is, in all but the most extreme conditions, precise to ±10 seconds per year. The regulation switch allows adjustments within this range. If a comparison were to be made, you could say that it is somewhat like the designation of a leap year to adjust the calendar. One gradation in the regulation switch is equal to 0.0165 seconds in a day, or 0.5 seconds a month. Since the movement has a precision that is 100 times greater than that of a highly accurate mechanical movement, the sensitivity of this regulation device is beyond remarkable.I recently acquired a SBGT237 and may want to regulate it in the future. (Although for the month I have had it the gain-loss is very close to +- 0SPY.) So far, I am amazed by the accuracy!
1. Does anyone have more history or technical information about 9F*** movement regulation?
2. Did the steps used to be 8SPY and now in 2018 they have been changed to 6SPY?
3. Have they always been 6SPY and mistakenly reported as 8SPY?
4. What is the source documentation for 8SPY steps?