We use to rebuild them when I was working. But I don't have the parts cleaner or compressed air here. Co-worker price was $20, non co-worker price was $30 for a cleaning, parts and time to get them was added. Exhaust screen may look good, but what is it suppose to look like? Oven cleaner does good, follow directions on can. Use a small parts brass brush to clean it. Blow the water out of it before installing it. Trash in the fuel, the lines in the carb are so small a speck of trash will clog them.