Greetings.
Yep, gun in right hand an turn the nob towards you.
Ive just acquired one on a gun.
Apparently you cant get spares realy.
Done do anything that might make the burst disc go as these are rocking horse.
In the valve if you take the bottle off, there are two white o rings, you can replace these with Automag on/off o rings apparently.
Dont use oil in the back, maybe a little grease on the spring and piston, thats it.
Good luck.