Dosing pump problems, Ph controler calibration

[woodchuck]

I got a complete grow box system with ph controler and dosing pumps and fluid level pumps.
I have greased the hoses on the doser pumps and they still wouldnt work so I called the compant Aqua Medic and they told me to install check valves they worked for a bit then quit.There tech support guy wasnt in so does anyone have experince with aqua medic doser pumps and can any one tell me how to get them working.
Thanks