One job was to sweep a chimney flue attached to an old stove. It proved to be a difficult job as the access from the stove to the flue was extremely narrow. Too narrow in fact for our traditional brush to fit through. We were unable to make the access bigger because the baffle plate was firmly fixed into position.
Our customer informed me that a previous sweep had said it was impossible to sweep because of this problem.
We were able to complete the job because we carry Rotary power sweeping equipment with us. This is far more flexible and was capable if fitting through the gap.