Most extended warranty companies will not pay for this repair, as it is not considered to ba a mechanical part failure, nor does Onan consider this as a warrantable failure. Although you should exercise the genset at least monthly, two months non-use time should not really be long enough to varnish up carb.
Check wiring from solenoid in carb. bowl, making sure grounding screw is tight on ground wire (black). If you have a spark tester, check for spark at plug wire.
have seen more than a few units with wiring damage from rodents (mice)chewing through magneto or coil wire..
If it is determined that carb is problem, it is probably better to replace it, as cleaning not always effective, as OP stated
