I followed the Gaggia MDF stepless mod but I'm not satisfied with the tape solution. It doesn't last in the time so I decided to use something to block the heavy force/rotation during power on using 3 small pieces of Filaflex.
Here is the original mod : http://www.home-barista.com/grinders/gaggia-mdf-stepless-mod-with-pictures-t10163.html
17/03/2017 This mod seems to work well. I noticed that it is better to push all the 3 Filaflex pieces to the center of the grinder. I don't know if it is ok wihout adding tape.