Only ever had an issue when harvesting peas when wet plant matter coated the deflector as SWMan says.
As to nicemustang's comment, he's referring to the fact that the Case rethresher doesn't seem to actually do reprocessing to small grains; it just recirculates the returns back around, building the volume higher and higher until it falls out the back, or causes grain to plug the cleaning fan. Either way (and on any brand of combine), high tailings load is a sign that you need to change rotor settings. And possibly open the bottom sieve up and close the top sieve to bring more air through to do cleaning.
So to answer your question, no we've never had a problem plugging the rethresher when going through kochia. Farmerjones assertions notwithstanding. We also have small tube rotors and they don't even groan with green kochia.
As to nicemustang's comment, he's referring to the fact that the Case rethresher doesn't seem to actually do reprocessing to small grains; it just recirculates the returns back around, building the volume higher and higher until it falls out the back, or causes grain to plug the cleaning fan. Either way (and on any brand of combine), high tailings load is a sign that you need to change rotor settings. And possibly open the bottom sieve up and close the top sieve to bring more air through to do cleaning.
So to answer your question, no we've never had a problem plugging the rethresher when going through kochia. Farmerjones assertions notwithstanding. We also have small tube rotors and they don't even groan with green kochia.