I'm linking this here so we don't lose it :

Andyspares Board --Diodes in hydractive valve

If your spheres (including the HA sphere) are gassed and everything appears to be working ... yet you have no 'soft' mode. See the link above.

Lets make this easy for google to find .... Xanita Hydractive Activa HA1 HA2 Citroen soft mode hard mode