Hi

I have an underfloor heating system in my basement, main floor and upper floor that has been working great for the last 10 years. Recently the higher up in the house the less heat I get. Upstairs my thermostat is set to 20C but am only getting 15C heat. Main floor is only a couple of degrees different and the basement is pretty close to what it is set at. The boiler heats my domestic hot water and still fires and heats up, I have checked the transformer and the thermostats open the control valves. My supply temp. is the same as the last several years. I have a Taco pump 0010-F2 on the system, I have tried replacing the cartridge but still the same problem. I was thinking perhaps the electrical portion if the pump? any thoughts?

Thanks