Yamaha Disklavier E3 Series Maintenance Handbook page 26

Shank stopper unit adjustment
When the quiet function is turned ON and turned OFF, both the shank stopper
lever and the MD lever will stop by touching each stroke end.
If either of them doesn't touch its end, there is stroke loss of shank stopper move.
It can be re-adjusted by using the adjust screw to get the maximum stroke
distance.
Check Step. 2 if the adjustment has been done.
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