Probably the firts thing I will asked is if the machine had a water softener installed and kept up with the regenerating,
second if possible ,plug the machine on and check for leaks and pressure building upand how long it takes , and if all possible and not sure about it open the boiler ( don't if you don't know what you are doing) and see the condition of the scale inside of it,
that's a start
ok, but what should I be looking for in the boiler and also how important is the water softner. I will also be asking for any repairs done to the machine and when was it purchased. Brand new runs for $6500, I was thinking about asking $1500 and go up from there.