greg bender
http://www.thisoldtractor.com/gtbender
I extracted this information from Mark Etheridge of Moto Guzzi Classics off of the Yahoo! Loopframe_Guzzi news group. In Mark's own words...
Have seen quite a few like this. I clean the inside out real good with carb cleaner, then high pressure blow it. Then I get heat gun and get collar real warm, then with a popscikle stick I put jb weld down there. The heat helps it kind of flow a lot better. Never had one leak or spin after doing this.