Grundfos AQtap Service Instructions With Installation And Operating Instructions page 38

5. Unscrew and remove both upper holders and one lower
holder of the control unit.
6. Slightly loosen the screws of the remaining holder of the
control unit. Do not remove the screws and the holder.
7. Take out the control unit.
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8. Unscrew and remove the remaining holder from the control
unit.
9. Replace the control unit by the new one Loosely fit one lower
holder to the new control unit without tightening the screws.