I just went through the process of cleaning my two 6100's. I find I put off the chore because they're permanently connected to that little box thing and I used nails to hold those in place.
So I have to soak them in vinegar with them sort of hanging off the tank. It would be so much easier to disconnect them from the box and take the pump to the sink and work on them there.
I seem to do it twice a year so far. Probably should be more often, but..
Anyhow I always find a calcium buildup in the bearings under the impeller. I wonder though if I actually tracked my magnesium and did something about the level whether this would be as bad a problem, since they say a higher magnesium helps hold Calcium in solution (or whatever it is).
I'm running mine on the 7095, although I'm not sure what's different about it that it would be better for buildup than the 7094.