Automatic Litterbox Central

Any thoughts on how to keep poo from sticking to the rake? I just cleaned the box yesterday and there's already a huge wad stuck to it! And cleaning all the stuck on-dried up poo is difficult, so anyway to prevent that would be helpful. My cat only goes in one spot, so there's always a mass at that end of the rake -- I don't know how the dried on stuff gets over on the other end!