new carbs look to cost in the $300.00 range. then there is the labor and filter. if your not going to use it or run it at least drain the carb of gas like they tell you in this manual on pages 27-28
onan handbook lots of good info on your generator. why do generator manufacturers use any type of electronic ignition shutdown on any generator the only method of shutdown should be gas shutoff and let it run dry. they could have separate temporary and storage shutdown switches i guess that would be too confusing or they like the repair money to much.