How do I fix a blocked pump on the UPS3 15-50/65?

Switch off the power supply, close the valves, then locate the deblocking screw in the centre of the control box and use a size 2 Phillips tip star screwdriver to push the screw inwards. When the screw can be turned counterclockwise, the shaft has been deblocked — repeat if necessary, then switch the power supply back on. The pump deblocking device is accessible from the front without having to demount the control box. (Page 17)