Welcome to CS.
a) if purchased new, suggest you could refer this to your retailer for advice
b) you havent told us what the pressure gauge indicates
c) you havent explained the "modus operandi" of the new "fault" ie does it happen all the time now (ie there is never any steam) OR only when you first switch on from cold but it subsequently recovers after the first time you open the steam valve.....
d) you will have to be more clear with your explanations otherwise we cannot understand what you mean.....lost presure in the steam wand....doesnt push any WATER out (do you mean steam, or are you saying no water comes from the group OR are you saying no water comes from the hot water pipe/wand).....AIR (?) with no steam (do you mean as in c) above).....
e) etc etc etc
IE...not enough information to be specific with advice, also, your information is conflicting.
Hope that helps.