What to look for when buying a used espresso machine

Im in the early process of oppening up a coffeeshop and came across used strada ep from a local roaster who is also an officaial distributor of la marzocco here. In all honesty wasnt planning to buy a used one but i am tempted considering the amount of money i will be saving (40% discount of retail price or about $6750). So im very tempted but i would really like to get some pointers on what questions i need to ask about the machine and what kind of inspection i should be doing.

i will be definately investiogation the following:

  1. corrosion and internal damage
  2. scal build up, plugged tubbing and sightglasses
  3. flow meters malfunction, and automatic water fill control unit failures
  4. external water pump (if it comes with one)
  5. portafilters

So i would deeply appreciate it if you guys can point me to whta other thing i should be inspection and what are your thoughts in general of buying a used espresso machine for a coffee startup.