Dual Tank Water Softener Advice

Hello H2O experts, We just bought an 18 year old home outside Omaha, NE with a well, water softener and reverse osmosis system. I am completely new to non-city water and was hoping someone might be able to tell me about the water softener pictured here. There are two tanks with a Watergroup Inc dial control on top. It is model 9100TMI-844-75. I was unable to find the manual online. I wanted to understand how to adjust for time etc and how to kick off a manual regeneration. Can someone share a user manual. I am not sure if the previous owner was putting salt in or if they performed any regular maintenance. Can you offer some advice to tell if the system is functioning properly and first steps for this newbie to take. Any help would be greatly appreciated. Thanks much - Ken