De-energise the pump. Remove the screw in the centre of the nameplate. The shaft located beneath this has a groove. Place a screwdriver in the groove and move the shaft in the direction of rotation until you have removed the blockage.
Modern self-regulating heating pumps no longer have a screw in the centre of the nameplate. However, the modern pumps have an anti-block feature. Should a blockage nevertheless occur, the pump head must be removed.
Caution: Hot water may leak out. Please comply with the safety instructions in the installation and operating instructions.