BRC not switching over

[Pogostik]

New on here so please bear with me.

Have an old BRC system which is not swithching over.
Car was filled but been sat for a while.

Guessing it's blocked filter and solenoid.

Question
1. can anyone identify this filter. FLO1S12/12. Is this a 12mm filter.
2. Solenoid is BRC ET98 standard with integral filter. Is this filter replaceable and is it a case of undoing nut from bottom.
3. Is the system under pressure. Can I undo this. (this is one of the reason not touched this so far).

Thanks