Sounds like you might need a descale, or maybe something is lodged in the gigleur (eg scale) which is blocking her up.
If you do a search for "scale e61" or "descale e61" you'll find lots of help as there are lots of threads outlining how to descale your machine.
The other thing you'd want to do is check the gigleur for blockage. Remove the mushroom (the big nut ontop of the group head), but be careful as the spring will make it jump out at you once it's loose. If it has white crusty chunks on it it needs a descale so do that. Carefully take out the little mesh tube and put it somewhere where it wont get bent. Get a socket wrench that's the right size, and very carefully remove the little nut that's down inside the group (the gigleur). You might need some needle nose pliers to get it out once it's loose, again be careful. Get a pin and ensure the tiny hole in the nut is clear. When you put the gigleur back in, don't over tighten it as it might break (like mine did).
Search as above and you'll find lots of help.