Jason,
There is a protected way to change the Hobbs and Tach time. We do not document it because it is not something that a user should normally be able to do. How do you change a mechanical Hobbs meter, tachometer, or your car Odometer? With an Electronics International Tach there is no way to change it.
If you need to change it call our tech support and we will talk you through it. As you already know, you can always reach me on my cell phone (503) 701-5042 if you need any assistance.
Rob Hickman
Advanced Flight Systems
N401RH RV-4
N402RH RV-10