Hi Red,
(Before trying this,make a test file first).
You can always "save (a component) as..." by right clicking on it (note that components are actually real, "independent" skp files "embeded" into your model - this will explain everything).
Now you save the component as a separate skp file which you can open and make any changes to. Note that you need to keep the axes for the further steps.
Now if you go back to your original file and right click on the original,still "unchanged" component, you can "Reload" it with (in this case obviously) the changed one you've just edited.
In your particular case, use this technique as it fits you. Instead of this, you can always copy elements (simple Ctrl+C) and paste them in place from the Edit menu (I actually have Shift+Ctrl+V assigned to this function) into the new model file.