Common reasons a Delonghi La Specialista stops pumping water?

The order listed by the original poster is basically the order I use and most other people I’ve seen doing these repairs. Nobody works on these machines without first checking the tank seating.
 
The flowmeter is the most common issue on these machines. I’ve done about a dozen La Specialista machines in the last 2 years. Half had the flowmeter issue then the solenoid and scale getting half the machines to the point where the pump will fail. The rest were actual pump failures or dumb issues with the tank seating.