If it (Generac not Onan) clicks but starter doesn't turn either main board not sending full constant 12v to starter contactor (starter solenoid)-
or contactor bad and not connecting battery power to starter motor.
Lastly the starter motor dead.
All easy to verify IF you were mechanical- but you said you were not and is not an option which leaves only finding someone to work on it. So only obvious option is increasing search area for someone to look at it.
That, I read, was Hawk12s question- suggestion for someone who may work on his generator in the Seattle area.