Had a dryer vent fire scare in a customer's laundry room last Tuesday
I was doing a routine drum roller job on a 12 year old Whirlpool in a house over in Milwaukie, nothing weird about it. Pulled the vent hose off the back to check airflow and a fist sized clump of lint came out with about a half inch of scorched black on one end. Turns out the homeowner had been running it that morning, smelled something hot, and just opened a window instead of calling anyone. I showed her the burnt lint in a ziplock bag and she went quiet for a minute. I ran a vent brush through the whole run to the outside flap and got another two cups of packed lint out of the elbow behind the wall. Used to be you'd see one of these every couple years, now it feels like once a month because everyone runs longer cycles on lower heat. What's your go to tool for a vent run you can't get to from either end?
That "opened a window instead of calling anyone" line got me, had a buddy whose tenant did the same thing. He got lucky, just a melted flap and a smell, but the fire guy told him the scorched lint was maybe one cycle away from lighting up. Now he keeps a cheap inspection cam in his van for runs he can't reach from either end.