Rain Soft water treatment system - Gold series - problem

We have a Rain Soft water treatment system - Gold series. This morning when I went to take a shower, there was NO water pressure. I checked the water filter and found that there was a constant drain flow. I thought that maybe it was just taking too long regenerating, so I bypassed the filter long enough to take a shower, then turned it back on before leaving. Eight hours later, there is still a constant drain flow going on and we have only a trickle of water coming out of our faucets. The owners manual says that the problem could be a "foreign material in composite valve". How do we go about checking that ourselves, without paying a technician $160, again?

Thanks!