figured it out ... sort of ... slicer placed code like :

G1 Z15 F100


which moved the z axis to 15 ... but centimeters???? where is the default units defined???

later the gcode from slicer says

G0 F9000 X221.399 Y218.399 Z0.300

if the F9000 is the movement rate I think, that is the equivalent to "ludicrous speed" for the Z axis, so I am not surprised
that the stepper just buzzes horribly ... just don't know how to fix that other than editing the gcode file

all movement only (non extruder) are G0 F9000 so I could edit fairly easily but what is good number?

am I right that all movement after F9000 will be that fast for all axis unless changed in the line of gcode?

any thoughts on what would be sane numbers?