Precix 9100 Controller - VI voltage issue Voltage range only 6.5 to 10Volts

I am having a problem with the Precix 9100 controller (built in 2000). The problem I am having is that the onboard speed controller pot is only adjusting the voltage from 10v down to 6.5 volts approximately. I am assumming the voltage should be in the range of 0-10v. I verified the range with DVOM when the machine is running. The slide bar on the software is all over the place at times also. It may run full speed when bar is in middle or 3/4 speed or 3/4 speed when at full. However, the voltage never drops below 6.5V approx. I do not know if it is a controller issue or software setting issue (Onyx OS). I am able to control spindle speed perfectly with Potentiometer though VFD but voltage does not drop below 6.5Volts. ANY suggestions would be greatly appreciated!!! --WOODY

Well It has to be a software issue. I should have checked it with voltage divider calculator.