Hello Voss Grose,
My advice here is to bind the Text property of the TextBlock in the DataTemplate, something like:
Then you will have to assign as Content of the ContentControl an object that has a property named MyProperty and afterwards you only need to change this object. If you want to change just this string, you can assign a string as the content:
dragCue.Content = "402"
and then use the empty binding in the template:
Hopefully this will work for you,
All the best,
the Telerik team