Is the engagement lever coming back all the way when you disengage it? Our 8820 was famous for not coming back all the way and doing what you describe. Under the seat and shield there is a linkage there that gets built up with chaff and stops the lever from coming back all the way. The only way to fix it is to reach in and remove the chaff by hand. Since the chaff gets compressed it is really difficult to get the chaff out. Just try to follow the linkage and you could find where its building up.