I have some friends who purchased a Krups Nove Plus machine from ebay. Worked fine for a few months, but now when they try and steam milk, the steam comes out of the group head instead of the steam wand. :(

Is this likely to be a blockage in the wand? Or a faulty valve somewhere? Ive never seen the machine, but was going to have a look at it for them. Any ideas on what the problem may be would be appreciated.