Your two screen trammel sounds very nice. I like the two size capture system. A fresh pile of individual worm castings at the right moisture is a thing of beauty for a gardener. Like running our fingers through gold dust. I am not an expert, just someone who sits on an up turned 5 gallon bucket looking at worms. To comfort you on these clods, if they are added back on top of the bin they are exactly what the doctor ordered. Even if you did not have clods and everything went trough the screens the bins, feeding some back would gain health with the addition of this microbe rich worm happy material. This material is not really lost. It eventually gets captured. It is just doing double duty for a bit. As for the clods I think that is why people pay big bucks for vermicastings. It is for that ability of the material to do that clod thing. It is a good thing for plant growing material to be able to do. Possibly the clods are what should be harvested as the good stuff and the finer not yet cloding stuff is what should be reprocessed. Then again they took the lowest quality diamonds and are selling them to hungry fake fingernail wearing ladies as chocolate diamonds for $$$.

I am sorry ti be of a different opinion to eqeq regarding the clod thingie.
Whenever I think a bin is ready for harvest, I did not feed that bin and soon the top will have nice fluffy VC, the longer I waited, more of this nice fluffy stuff got produced. The worms hang out just below this layer. When I put the contents of the bin through a sieve that I use to screen the VC, I did get these clods and IMHO these are not totally finished VC. After a month or 2 storing this harvest to cure and age, these clods will break down into nice fluffy stuff. It is possible that this is the result of what the mites did or just time and evaporation, I'm not sure.

Thank you otis11. Interesting thought. We are taking over the management of a number of bins. After harvesting a couple, we concluded that they had been overfed. We stopped feeding for the last several weeks to see if we could encourage more complete processing before resuming normal feeding. I did not relate the clods to under-processed compost. Will experiment.