The first step in replacing the desiccant is to remove filer wheel.  This exposes the CCD/desiccant chamber.

Next, using the 3/32nd hex wrench, remove the CCD/desiccant cover.  This will expose the CCD chip and wiring, and the desiccant pack.  Be very careful not to touch or damage the CCD chip.  Also, note the rubber O-ring that has most likely fallen out of the bottom of the chamber housing.  Leave it where it is.  The desiccant pack has most likely been modified with adhesive tape to help it conform to the small interior of the housing.  Similarly modify a new desiccant pack and replace the old one.  Then, clean the surface of the chip with compressed air.  Under no circumstances attempt to clean the chip with anything else! Replace the chamber housing, assuring the rubber O-ring is properly seated underneath and is not being pinched by the housing.  When tightening the screws, take extreme care not to strip any of them.  Reinstall the wheel and front cover.