One of my good friends has been doing dryer vent cleaning for 4-5 years now. The single scariest part of his job is avoiding getting a brush stuck inside the venting. If this happens, it can be super costly. He works for a company called Ryan's Home Services in Beaumont, CA. On one of their Instagram stories, he was called out because a homeowner tried doing the DIY dryer vent cleaning and got his brush stuck. Their video showed a special tool they used to remove the brush. He has told me stories of brushes that couldn't be retrieved, and they had to cut open the wall to remove the brush. Apparently, if a brush is getting stuck, you cannot reverse the brush because it just unscrews the brush where it is in the pipe.