The small white gear is located on the brew group gear motor. If you hear the brew group motor running, but the brew group is not moving at all, or is moving erratically with a very loud chugging noise, then it's very likely that the problem is that this small white gear is cracked or split. This happens as the plastic ages and becomes more brittle. The crack can be hair-thin and may not be obvious at a first glance, so if you have the symptom mentioned, examine it carefully and you will probably find out it's cracked.

This fits all Jura and Capresso super automatics.