PCSGU250 Function Generator Output is not 0V when output is off

Good day. I have an issue with the function generator of the PCSGU250. The output of the generator always starts at +110 mv DC at rest, and AC waveforms always have this DC offset, unless I set the offset via the software to -110 mv which then corrects the waveform, when when waveform is stopped, the +110mv DC reappears.
I have a use that requires good control of the DC bias during waveform switching and the this anomaly is causing an issue with the measurement. Is there some way to null the output to 0 while waveform is stopped?
Thank you.

Yes, there is trimmer potentiometer RV1 on the circuit board to adjust the offset.
You have to open the screws at the bottom of the unit and remove the cover and then remove the circuit board.
Connect the USB cable and run the software PcLab2000LT normally.
Keep the function generator stopped and adjust RV1 until the offset is about 0 mV.