If you find recirculation comes to a complete stop:

1. Turn off your pump and remove the recirculation arm.
2. Carefully unscrew the ball valve from the top of the recirculation pipe (the ball and spring are contained within so be careful not to lose these).
3. Check the inside for any obvious blockages and remove this. You can also check down the recirculation pipe.
4. Once any obvious blockage has been removed, reattach the ball valve and recirculation arm and start your pump again.