Gas valve failing to open on ferroli domicompact f24b?

My boiler has been working fine, used it last night before bed with no problems or noises.
Woke this morning no hot water or heating- F1 fault. Tried reseting- no good. Checked gas flow to boiler seems healthy enough, igniter/sparker fires but no gas flow to manifold. The main solenoid on the gas valve energises and magnetises also checked the monureg solenoid next to it (not sure what this does- think it senses pressure variations?) it has voltage to it but thats as much as i can say. Stripped out valve to see if there were any obstructions- none to be seen. Checked pcb nothing there either, no dry joints or suspect components no bad smells ... nothing.
Could this be a mechanical failure of the gas valve or have i over complicated a simple problem?
All advise greatly appreciated.
Regards David

ps my next door neighbour has just had gas plumbed into their house from the main in the street a week ago??