Ferroli Otimax HE38C?

Yes they can stick, take cover off, you will be able to see valve, some have an actuator on one side going to micro switch, watch it does it move when hw called for, does it move back? If not stuck, possible to get overhaul kits for most makes, look on Ebay, But would depend on why it is not moving, Listen to it, can you hear some motor move.
If no switch on side, listen for it moving, usually hear it, switching water on/off Also check your pressure, should be about 1 bar cold.

SD
December 2011