Hey Stan,
Purge scripts are set to run once a year, once a month, once a week and once a day as there are four procedures that run both to collect and purge data. You can manually run the purge by just right running the default stored procedures in SQL Management Studio after connecting to your Virtual Center DB and that would actually run fine, and I am guessing the max.Age parameters are what you would already find set to 6 months in the scripts if you already have made the changes in the GUI!
Thanks
a