Encoder module failure?

I'm using an AX1500 in single channel operation with encoder module. I'm using both the encoder channels but today the second one stopped working. Its RPM value is not valid anymore (compared to the first channel). Moreover the Switch 3 light is always black, while the switch 4 is red. Can you help me?

Disconnect the encoder and check that all inputs are black. Check your wiring and that there are no cut wires. The encoder module practically never fails from our experience.