I have a Nespresso Aerocinno + but my kitten has hidden the small black plastic "latte" milk whisk. Any idea where I can get hold of a replacement?

There are no moving parts in the frother other than the whisk assembly. The whisk assembly is spun magnetically. I am not sure if it is possible to have the magnet in the whisk assembly in the wrong orientation, but if so, be sure that it is reassembled with the magnet side down. Additionally, if I haven't removed the whisk in a while (I normally just immediately rinse and wipe the interior with a cloth) then the metal stem can build up with milk solids... and cause the whish to "stick"... the magnetic force is not exceptionally strong and it could be that the plastic assembly is "sticking" on the metal post... pull off the whisk and give the post a good wiping with a wet cloth to remove any possible residue.

Use the bar-style spinner and run it twice.

I found that switching to a different milk solved my issue. It worked well with whole milk, but when I used Trader Joe's two percent organic it would not froth after .multiple tries. I borrowed a neighbor's creamer and it worked again.

Contact the Nespresso Club at 800.562.1465. The replacement frothing/steaming whisk set, item number 13192/6, is currently available for sale at $2.95. .Shipping is flat fee of $6.95

The last couple of times I have used my milk frother on my Nespresso Magimix has overflowed creating a mess. Its almost as though the pressure builds up and forces the milk to overflow. Any ideas?

They sell the parts at the Nespresso.com, I also saw the frother for sale on ebay

The small black stirrer doesn't froth the milk; wherease, the one that looks like a whisk froths the mil to make foam. So, if you want warm milk without the foam, use the black stir (it still makes a little froth) and if you want lots of foam, use the sliver one that looks like a whisk.

Call Nespresso customer service at 800-562-1465. Replacement set of 2 wisks were $2.95 + shipping

both parts can be found on amazon for about 9.99$. take a look here: Secura Automatic Electric Milk Frother and Warmer Whisk Set. I hope this was helpful. cheers