Rain Soft Water Softener Gold Series--Need a Manual....

I have a Rainsoft Gold Series Water Softener, circa 2001. Per the unit, it is a AQC75CT. We are having some problems with it as our water seems to not be as soft as it had once been. We have read there is a "secret" manual and are wondering if anyone out there still has a copy of this. We have discovered how to use the raindrop button to reach the installer programming portion, but would like some info as to what all the codes mean. Can anyone help us? Thanks so much!