The standard control panel only offers a red light when the cassette is over 3/4 full.

With the 250 model in particualr it suffers from condensation damage (cured in later 260 models).

The replacement panel gives LED warnings when the cassete is 1/4 full, 1/2 full and over 3/4 full.
It also gives a flashing RED LED if the cassette has been removed for emptying.
As regards to the condensation problem. This caused the Edge Connector to fail. The replacement can have eaither the edge connector or screw terminal, allowing the old edge connecttor mounted on the wires to be removed and clamped instead.

It also operates an extraction fan that can be installed either in the designated fan location or better still under the floor. the fan will operate for approx 2 minutes after the flush has been operated. 

Don't be put off because of the SMD componets. They are easily soldered by hand.