Replacing batteries in your Pro-Control module is easy.  Simply remove the two solution cup housings, and place the module on it's top.  Keep the manifold attached, replacement is easiest if you place the control over the edge of a table.  

Remove the (4) screws from the main body with a #1 Phillips screwdriver.  Pull the top cover off your module, revealing the internal components of your Pro-Control.

Inside, you will find the battery box.  Slide the lid off to expose the batteries.  Replace all three batteries with (3) Dry-Cell "C" type batteries.  Reverse the process for reassembly.  

Battery life is dependent on usage but expected life is approximately 4-6 months.  

Hydra Rinse recommends replacing batteries with a Pro-Control Tune-up kit to ensure optimum performance, of which can be purchased from your local Hydra Rinse  Distributor.