Well I understand your pain but the problem is with wintering any espresso machine is you never truly get all the water out. So even if that water does freeze or if you keep the machine in a heated space will eventually evaporate over time. When that happens it will leave scale deposits. Your Cimbali has a few flow jet restrictors and they are where we see the most problems arising from wintering. It only takes a small amount of water to dry up and plug that .5 - .8 mm hole leading to the group head.
Now you can do your own winterizing of your machine. There are some places who take an air compressor and hook it up to the water inlet and charge the system up to around 90 PSI and blow the water out of the machine. The only problem with this is you have to have the machine on to open up valves to drain all the water. If you want to take the time to disconnect the pump motor this will help increase your pump life. Its not meant to pump air and to top if off running dry can kill a pump PDQ!
I also take mine a step further and remove those jets for the winter. In a M29 Selectron there are 4 jets on a 2 group. 2 @ the group head, 1 @ boiler inlet valve, 1 @ cold/hot water injection valve. Upon removing those after blowing it out will allow any excess water to drain away. That and at the beginning of the new season you'll know that your machine had a PM and should be running like a champ all season long.
Thanks!
