Machine will not run out to top speed
In what way..? Engine will not reach max RPM, transmission not upshifting, etc..? You don't give us much to go on. IIRC the small G series have a programmable gear shift that can be used to limit ground speed by limiting the maximum forward gear.
hydrostatic transmission on these. Check if the creeper speed valve is closed to begin with.
Ooops, my bad. I was thinking 924G.