Thanks Stephen,
When I was poking around the file system via ActiveSync (I feel like I'm in a time warp working with Windows Mobile again) I noticed the agentry.ini file contained the IP address of the server. Could I have just modified that instead of clearing the device?
Anyway the machine name is now working for the Windows Mobile device to the Agentry server. For some reason it isn't working for my iPhone or iPad but the IP address is and I can easily reset the client on those devices.
By the way the Agentry Test Environment (v6.0.46.0) does have a Reset Test Client menu option under Test.
Thanks again,
Dave