Look on the back of the top coveer and you can get the model # Sears web site should have the manual on line. Not sure what good the manual will do you though. Suggest you operate the "BYPASS" valve located where the water pipes come into the softener. This will let you know if
the problem is in the unit or somewhere else.I beleive this unit is a single tank. The drain is a pplastic tube coming from the same area as the incoming water lines.