Unfortunately I dont know the necessary size of the Torx-TR for the Polti Vaporetto deep-screws yet, but I can probably contribute a useful link to a tools collection:
http://www.pkelektronik.com/index.asp?GroupID=660
search for:
"Wiha TORX Tamper Resistant-Schraubendreher 362TR SoftFinish T20H x 300 mm"
unfortunately for me, WIHA does still not resell directly in Austria, this may apply to more countries other than Germany.
Greetings to all of you and thanks for your helpful instructions!
clemens
February 2009