Well I have been a bit daunted by the complexity of the machine, so
have decided to print out the helpful procedures at the Jobo USA
website so that I might minimise self-inflicted damage through
dissembly.

All ICs seemed to be seated correctly and not any obvious damage to
pipes/connections. Haven't found the wire sensor yet.

The other fact that I forgot to post, but on reflection would seem to
be relevant is that when performing a cleaning routine, the fault has
never occurred i.e. the bottles are emptied completely irrespective of
the volume of water I have put in.

Baxter