I have the same type(though sold by Sears). You should look at part 130
in the "pump" diagram. This contains every thing you'll need for rebuilding
the rotary valve. The disassembly is pretty straightforward. Put the
softener on bypass, unplug and take apart, clean everything up, smear
plumbers grease on all the new rubber parts and reassemble. I always drop
the small spacer(part 140) so try not to lose this.