A: Firstcheck the inlet filters on the pump if they are OK then it may be a faultyimpellor or the motor brushes are starting to fail, in any case this pump isvery difficult to work on in my opinion you are probably better just replacingthe pump.
http://www.showerdoc.com/showers/shower-pumps/triton/ZTRITO-T550I00M-Triton-T550I Shower-Pump---1-2-Bar-Twin
Answered 122 days ago | The doc