A word of warning on the above, only takes an uncomfortable minute to check !
Checking out the function of the float switches I found out that the lower switch was lifting a little then sticking and not switching on.
On examination I discovered that Siltala had inserted 2 electrical cable clips under the switch flange to lift the switch above the bottom of the pump basket. Unfortunately because these clips did not support the switch across the whole width, the switch base was bending down in the middle. The bend caused the two locating vertical pivots to bend inwards and clamp on the switch body. Solution was to place a thin aluminium plate under the switch above the clips so that the switch base was flat.