The enzyme tubing may be clogged. Look at the enzyme tubing from the reservoirs to the Enzyme Pinch Valve and beyond to the Manifold. If there is any discoloration or gelled material in the tubing, replace the tubing.
Contact ANKOM Technology at https://www.ankom.com/contact/technical-services or 1-315-986-8090 to purchase your Enzyme Tubing Replacement Kit (TDF67).
Refer to TDF Service Procedure TS004 for Enzyme Tubing installation instructions.