Hi Fred, I have Operator's Manual for B414 witch is the older model. The book only describes how to set the clutch pedal adjustments and not how to adjust the dual stage clutch internally.
Here is clutch pedal adjustment:
1)7 inches of free travel from floor board to rest position. Adjust by adjusting bolt on clutch arm.
2)1/2 inch free travel. Adjust by loosening bolts on clutch arm at clutch release shaft and rotating clutch release shaft.
I belive if you search the archives for B414,434 or 444, someone posted the procedure to adjust the dual stage clutch through the inspect plate under the bell howsing.