Pascal, my ball shaft seals failed because when the pedal was depressed, the action created a torque/twisting between the shaft and the base. I was told that this happened because the pedal was allowed to travel too far downward because the unit sits on a slightly elevated shelf and the pedal overhangs that shelf. Without something to stop the downward travel of the pedal, it will create this twisting effect and mess up the ball shaft seals and other things within the base. Of course, this could easily be a one-time unique event (they seem to happen to me frequently) and I haven't had any issues since the repair. In fact, the vacuum now hold longer than it ever did. I was gone from the boat recently for 2 weeks and when I reapplied power, the vacuum generator did not have to top off. I was amazed!
