After 20 roasts the chaff collector should be emptied and this is very simple and the roaster will let you know it's time. A ventilation grid should be cleaned when needed at the back of the roaster, about every month depending on the environment. Every 1500 roast or so the ventilation should be cleaned by taking off the top and accessing the drum. 15-minute job. Every 6000 roast or so the chaff separator and fan system should be cleaned. This is a 2 hours job but ROEST does offer a cleaned system for replacing as well.