You really don't need to disassemble your racks to treat them for mites. Yes, mites will lay their eggs in cracks and crevices and those eggs are pretty impervious to just about anything so there is not much you can do to kill the eggs. What you CAN do is spray with a permethrin based poison like Provent-a-mite. The beauty of provent-a-mite isn't that it kills mites, it's that when properly applied it continues killing mites for months. This way, it kills the baby mites as they hatch which will break the mite cycle so you don't find yourself being re-infested over and over and over again.