Ok now will you explain to me WHAT a cap is? Does that mean a hard surface?That packing down is not a bad thing unless it is proving to be a "cap". Eventually the litter has to pack down and remain undisturbed at the bottom in order for the various bugs, worms, larvae, bacteria, etc. to start decomposing the material. If it is clumping together on the surface of the litter, then turn it over and into the dry litter...it will dry out and get blended in with the dry litter.
I never rake my litter but occasionally if the birds are not tossing the top of the litter very often, I'll take the pitchfork and place a fork or two of litter over the manure directly under the roosts. This doesn't happen very often and one doesn't have to disturb the litter pack too much to accomplish this. Just the looser and dryer upper layers.