Because the interior unit has a pump with moving parts, the unit can wear out and need replacement.
Some parishes have noted that in some units the fill level sensor does not work consistently. This happens because the dispenser was originally designed for liquid hand sanitizer and re-purposed for water. In some cases the sensor cannot detect water level because water is slightly less dense than liquid sanitizer. However, this does not effect the pump, and so the dispenser will still work properly.