Why is the La Specialista Arte steam wand not performing very well, as before? I noticed the foam is not the same as it was when I just purchased the machine.

Just like a Barista would do when using a commercial machine it is important to clean the steam wand every time you use it to minimise and build up of milk residue. Simply flush the steam wand by pointing the steam tip into the drip tray and turning the steam on for a few seconds then wipe the steam wand clean with a damp cloth.