2017 Warwick duo

I hadn’t spotted the original post in the link above and have now answered it based on a similar experience. The spring assists the lever action and isn’t connected with the cassette-full indication. The latter operates on a magnet attached to a float in the cassette, which activates a reed switch when the level is approaching the full state. The reed switch closes a circuit and lights the red LED.

The most likely explanation for your faulty indicator is the float arm being stuck in the “full” position. It’s time to don your Marigolds and clean the cassette interior thoroughly. If you don’t fancy that you can purchase a Thetford “freshen up” kit comprising a new cassette and seat/lid.

Tim

To clarify, the lever won’t return automatically, you’ll always need to do that manually even with the spring connected. But with the spring assistance you’ll need slightly less oomph to operate it.

Tim