The gap is usually adjusted by adding or removing shims located on the compressor shaft just behind the clutch hub. They're like small washers. But its rare to have to add shims. It usually works the other way around. I would check the hub plate and springs themselves. You could have a broken hub plate spring. Turn the hub by hand,(engine off of course). See if the hub rotates evenly and the gap doesnt change. If it does theres a broken spring and you'll have to replace the hub.