The boys are telling you the truth, hard to find for parts. Action Products out of Tempe, AZ is where they were located. The Briggs engine was a special with an extra long crank to accommodate the timing belt clutch which was spec out by the company. The timing belt was 5mm pitch versus the 8mm you would find on a racing enduro kart. The karts were originally designed for Sears and they cancelled the contract so then what the heck do you do with 10,000 karts? You put logos on them and sell them to gas stations for promotion grand openings and car dealerships for give a ways with the purchase of a new car.
The downfall was the plastic drive wheel with the brake drum attached to it. Brakes generate heat, heat warps plastic and then you quickly have an out of round wheel. Like the boys suggested it isn't worth restoring. But it did have a GREAT CLUTCH.