Osmolator metering pump does not pump higher than 1 meter

[fmuakkassa]

I have had a Tunze Osmolator since October 2007 and it has been working fine. I have replaced the metering pump many times as they stop working after couple of years. The last time was Jan 2018.
Couple of weeks ago, I noticed that no RO/DI water was being pumped in the aquarium. I checked the pump in the RO/DI reservoir and it was spinning with no air bubbles. I changed the 1/4" tubing (thinking it was the problem) and whenever I raise it about a meter above the base of the pump no water will flow. So I ordered a new metering pump and installed it and had the same problem. The height from the base of my Rubbermaid RO/DI reservoir to the top of my aquarium (where the 1/4" tubing ends in the return) is about 5 feet (153 cm).

So what is going wrong?
Could the controller go bad and not deliver enough current to the metering pump? The controller has an Ac voltage adapter set at 9 volts (the one that came with the osmolator)

I have a lot of evaporative loss daily in a 180 g reef aquarium with open top and metal halides. The osmolator is indispensable for my aquarium.

What should I do next?

 

[rvitko]

The most probable is the circuit board is failing, given the age and the older circuit board design, likely the PTC or a transistor has overheated and is damaged. The only simple possibility is that the wiring or connector for the pump is corroded, in that case cutting back the wire to the pump from the controller to clean shiny copper and replacing the terminal connector would resolve the issue. Otherwise it would be time to replace the Osmolator.

 

[fmuakkassa]

Thanks. I did trim the wiring and reconnected but nothing changed. I ordered a new Tunze osmolator.

 

[rvitko]

Thank you.