Removal, dismantle, clean and re assemble did the trick.
1.Invert the tube and carefully prise open the indents that locate the bottom plug to the metal tube. Gently remove the plug taking care not to let the float drop off.
2. Keep the unit inverted, and Lift out the 3 no indents that locate the top plug to the metal tube.
4. Carefully withdraw the metal tube.
5. Gently ease apart the two sprung loaded contacts, taking care not to pull them too far apart, and slide the float off of the circuit board.
6. The circuit board is located into the top plug and held in place with 3 No spring loaded contact clips. Gently pull the board from the clips using a rocking motion. care required as the clips may spring off.
7. Clean all contact sutfaces, I used that powder for cleaning copper bottom sauspans, but any mild metal polish would do.
8. Then reassemble in reverse order. Note! The 3 small contact clips can only be replaced one way
Good Luck
