Sudden Loss of Power on Silence 1073.050

[tpallas]

Hi - I've had a Silence controllable pump as my return pump for 2 years. Suddenly, this week, the output dropped significantly. I've cleaned and inspected and don't see any obstructions. When I adjust the control knob, there is a change in the ouput, but not to the amount that it was producing. At max output, it was unable to push 3 feet of head at max power. Any input you could provide would be appreciated.

 

[rvitko]

Any chance the bushings are seized onto the impeller or the impeller has some physical damage (worn down shorter or thinner)? Water damage to the potentiometer or a drop in power supply voltage are other possible causes, if you have multiple Tunze pumps, it could be a power supply was swapped so it now gets 18V instead of 24v?