Have an old (possibly Fleck 9000?) softener, brine is not drawing in. Checked the assembly in the brine tank, everything is clear -- can blow/suck through it, marble floats like it's supposed to. Not getting suction through the line, but am getting water back out to the tank when it's time to refill (although it's pretty slow.) I assume it's a clogged valve, thought MEP or someone might be able to point me in the easiest way to check, and which valve it probably would be..?