The steam from brewing goes up into the grind the chamber and results in caking of the residual coffee grinds. Extensive cleaning is acquired between each use.
I inherited a 650 that finally bit the dust. Was going to get another, but not available. Cuisinart phone rep suggested the 450. Really like it. Easier to clean than the 650 & doesn't get as messy. Dishwasher safe for cleaning.
I had used the prior iteration of this machine for 10 years before the burr grinder suddenly died. While I am sad that the hopper on top is now gone (thus you have to fill the blade grinder each day), and that the stainless steel carafe is no longer available in 12 cup, but now 10, this still satisfies.