Bought a $35 borescope off Amazon and it paid for itself on my first call
I had a dryer at a house in Tempe last month where the vent run went up through the attic and I could not see the clog from either end. I grabbed one of those cheap USB borescopes with the light on the tip, figuring I would try it once and toss it in the drawer when it did not work. It showed me a bird nest about 12 feet in, and I pulled it out in maybe 10 minutes instead of cutting into the wall. For a $35 tool that is a pretty good trade on one job, but I am wondering how long the little camera holds up after it gets bounced around in the van.
Mine rode around loose in the van for about a year before the usb end got bent and stopped connecting. Now I keep it in a cheap hard case for sunglasses and it's been fine since. Wrap a little tape around the cable right where it meets the plug too, that's always the first spot to go.