My book says parameter 3772 is Maximum Spindle Speed
To change VIA G10:
G10 L52 ; Parameter entry mode setting
N3772 R12000
G11 ; Parameter entry mode cancel
N_ : Parameter number
R_ : Parameter setting value (Leading zeros can be
omitted.)
P_ : Axis number 1 to maximum controlled axis number (to
be specified when an axis type parameter or spindle
type parameter is specified)