I think the electronics in this device are sealed, so there is no way to repair or replace the electronic components. Harley Davidson doesn't seem to provide any support for this item outside of sales. I contacted Harley Davidson, and they said they didn't have any information on the device. You can try checking the wiring connector to make sure all wires are clean and connected properly.
I noticed on Harley Davidson's website that this item did not get very good reviews and several people had problems with the device.
If you find any information about your gear indicator, than please post it hear so others can read the info.