If it’s the same problem as my G68, then it can probably be fixed by a good clean rather than replacement. The volume control on my G68 became unresponsive – large turns of the knob only resulted in a small volume change and sometimes small movements of the knob resulted in random volume changes both up and down. Is this your problem?
On the G68, the volume control is on the end of the board that has the display unit on it. If the G02 is similarly designed, you could try the fix that worked for me (at your own risk of course). You would need to acquire a few 100 ml of high purity ethanol (alcohol). Pure enough such that won’t leave a significant residue. (High quality methanol would also be OK but not acetone).
I removed the board from my G68 and covered the display part with a small plastic bag and carefully sealed it with tape leaving the end with the volume control exposed. I then bathed the volume control with ethanal turning it repeatedly (obviously taking care to not to expose other parts of the board to the solvent). You could also use a small syringe for this. After about 5-10 min of washing I allowed it to dry and then reinstalled it in my G68. It worked perfectly and continued to work until I parted company with my G68 about a year later.
Main system - Sources (Kodi-HTPC, Vero 4k, FireTV, Sat) into Trinnov Altitude 32 (8-16) (+Roon), Trinnov Amplitude 8 amp & Vivid Audio (Giya G3, V1.5) and REL Stentor III speakers. Others: F80 + Raspberry Pi and other Pi systems.