Thanks Gra. It certainly doesn't smell. I think I've found what the issue is with the wand. I think it's the tap (the handle part that is). I've attached a few photos. 
I took the HW tap off, and compared the too. When you unscrew the tap the part with the stopper moves out. With both fully extended you can see the difference. The HW tape extends a lot longer out. With the steam tap it seem that it screws out at the same rate, but on the final part of the turn it stops, were as the HW tap kept going until fully extended. I then took the chrome vapore cap off, and it came off quite easily, and inside there was a lot of fine brass shavings. I also noticed the the plastic around the brass has cracked and I think this is the issue. I tested the tap, and sure enough as it turns the stopper extends, but on the final part where it stops the plastic turns on the brass and the brass part starts to pop out!!! I took the whole mechanism apart and it's all in working order so by my observations I am certain the the plastic handle part is the cause. You can't seem to remove this from the brass part either. I can't get the chrome HW tap off. Hopefully Jack has a spare tap for me. Still not sure what the black stuff is and I'm waiting for a response from QM.
