Leaking steam valve rancilio miss audrey

you should take out the knob first, than you try to disasembke the SHAFT of valve from the valve body, in this types(small espresso coffe machines) usualy producer use conical valve, without seals she close metal to metal, when you get out the SHAFT you will see one line on the conical end. for repairing it will be enough to visit one metal vorkery where they will take a small amount of brass from end and polish it. then you put it back and work again with your machine.

ps: notice you only polish the SHAFT , dont let them to short the more than 0.5 mm