If its a year old what about warranty?
Best thing before throwing a carb on it would be get somebody else to give it a look.Could be something you aren't seeing, its hard to TS from here and everyone here has given excellent suggestions but without being there makes it tough.
I'm sure Home Depot has someone contracted for maintenance.
Another thing, they usually stand behind their merchandise, go up and tell them your problems with the unit and how you spent all this good money and so on.They might eat the repair.