In order to do a thorough  job we need to create accesses into the ductwork.  This can be to attach the general extractor hose, or to get brushes or aggitation tools where they need to go. Here are some pictures of what this all means.  Most important to you, is how we secure the accesses so your system works as it should.   Here is a picture of a place where we connected the general to, and patched using a metal patch, placing adequate numbers of screws on it's perimeter to ensure a proper seal.

To ensure a proper seal we put tape around the opening.

And for those places where we need a smaller hose, we use a plastic plug that fills in this tiny opening..