Water flowing too slowly into Brine tank of EcoWater softener

I have run the manual re-charge diagnostic on my EcoWater softener. I think it failed the first step, where the water is supposed to flow into the brine tank. All the other steps seemed to go OK. So, my DH and I took a look at the venturi and nozzle, screen and the flowplug and they were all very clean. I am puzzled. I know that the water didn’t go in very fast, because there is a water meter on the house right “in front” of the water softener, so we can see if the little dial is going around – and it was barely moving…
Any ideas what might be wrong? This unit came with the house – it was installed in 1998.